AUTOMATED ONLINE MINERAL SLURRY AND PROCESS WATER PH ANALYZER, QUANTITATIVE VOLUMETRIC TITRATION ANALYZER, AND LIQUID HARDNESS ANALYZER
20230393076 · 2023-12-07
Inventors
Cpc classification
G01N1/2035
PHYSICS
International classification
Abstract
Automated analyzers to measure or determine parameters in mineral slurries or process water, in particular to online and automated analyzers to measure pH, or to perform quantitative volumetric titrations relying on spectra absorbance of a liquid extracted from titrant and titrant mixture to determine the endpoint of titration, such as the measurement of liquid hardness in mineral slurries or process water. An automated pH analyzer may include a processor operable to manage the operations associated with the apparatus, an automated sampler coupled to the vessel or conduit and operable to extract a sample of a determined volume of the slurry or process water from the vessel or conduit, the automated sampler being under control of the processor, a water source under control of the processor and operable to deliver a known volume of water of a known pH into the sample, a mixing chamber that receives the known volume of water and the sample, an agitator operable to agitate the sample and the known volume of water in the mixing chamber to produce a diluted sample mixture, an automated filter operable to extract an aliquot of the diluted sample mixture from the mixing chamber and to filter the aliquot to produce a filtrate, a pH probe after the automated filter to measure the pH of filtrate, and a pH probe within the mixing chamber operable to measure a pH of the diluted sample mixture. The measurement is used to calculate the pH of the extracted sample, and to alter in near real time a process control of the a mineral processing operation related to the mineral slurry or process water.
Claims
1. An automated pH analyzer for determining the pH in a mineral slurry or process water in a vessel or passing through a conduit, the apparatus comprising: a processor operable to manage the operations associated with the apparatus; an automated sampler coupled to the vessel or conduit and operable to extract a sample of a determined volume of the slurry or process water from the vessel or conduit, the automated sampler being under control of the processor; a water source under control of the processor and operable to deliver a known volume of water of a known pH into the sample; a mixing chamber that receives the known volume of water and the sample; an agitator operable to agitate the sample and the known volume of water in the mixing chamber to produce a diluted sample mixture; an automated filter operable to extract an aliquot of the diluted sample mixture from the mixing chamber and to filter the aliquot to produce a filtrate; a pH probe after the automated filter to measure the pH of filtrate; and a pH probe within the mixing chamber operable to measure a pH of the diluted sample mixture, wherein the measurement is used in any one or more of following: to calculate the pH of the extracted sample, and to alter in near real time a process control of the a mineral processing operation related to the mineral slurry or process water.
2. The apparatus as claimed in claim 1, wherein the apparatus is online such that the sample is withdrawn from an online active process.
3. The apparatus as claimed in any one of claims 1-2, wherein the processor is operable to instruct the automated sampler to extract the sample from the vessel or conduit.
4. The apparatus as claimed in any one of claims 1-3, wherein the water source delivers the known volume and known pH of water to the automated sampler after the sample has been extracted to flush the sample out of the automated sampler and into the mixing chamber.
5. The apparatus as claimed in any one of claims 1-4, wherein the processor is operable to instruct the water source to deliver the known volume of water to the automated sampler.
6. The apparatus as claimed in any one of claims 1-5, wherein the water source cooperates with the automated sampler to deliver the volume of water into the extracted sample to flush it out of the automated sampler to clean the automated sampler thereby ready it for obtaining a subsequent sample of slurry or process water.
7. The apparatus as claimed in any one of claims 1-6, wherein the agitator is controlled by the processor.
8. The apparatus as claimed in claim 7, wherein the processor is operable to activate the agitator to mix the sample mixture after the sample mixture is received in the mixing chamber.
9. The apparatus as claimed in any one of claims 1-8, wherein the processor is operable to receive the pH measurement of the diluted sample mixture from the pH probe within the mixing chamber after a period of agitation of the diluted sample mixture.
10. The apparatus as claimed in any one of claims 1-9, wherein the water source is operable to flush water through one or both of the automated sampler and the mixing chamber, after the pH measurement of the diluted sample mixture, to clean one or both of the automated sampler and the mixing chamber in preparation for processing a subsequent sample.
11. The apparatus as claimed in claim 10, wherein the processor is operable to activate the agitator while the water source is operable to flush water through the mixing chamber.
12. The apparatus as claimed in any one of claims 1-11, wherein the automated filter comprises: a second automated sampler coupled to the mixing chamber and operable to extract the aliquot from the mixing chamber after mixing the process sample with dilution water; and a filter element downstream of the automated filter, wherein to produce a filtrate and the pH of filtrate is measured by the pH probe installed after the automated filter.
13. The apparatus as claimed in any one of claims 1-12, wherein the processor is operable to calculate the pH of the sample using the known volume of the sample, the known volume of the water delivered into the sample, the known pH of the volume of water delivered into the sample, the measured pH of the diluted sample mixture, and the measured pH of the filtrate.
14. A method of determining a pH in a mineral slurry or process water in a vessel or passing through a conduit, the method comprising: a. coupling an automated sampler with the vessel or conduit such that the automated sampler is operable to extract a sample of a known volume of the slurry or process water from the vessel or conduit; b. providing instructions from a processor to the automated sampler to extract the sample; c. flushing the sample from the automated sampler into a mixing chamber with a known volume of water having a known pH from a water source under control of the processor; d. mixing the sample and the volume of water with an agitator in the mixing chamber under control of the processor to produce a diluted sample mixture; e. measuring a pH of the diluted sample mixture with a pH probe in the mixing chamber under control of the processor; f. extract an aliquot of the sample mixture, filter through an automated filter and measure the pH of filtrate by a pH probe after the automated filter; and g. analyzing the pH measurement of the diluted sample mixture and filtrate with the processor to determine a pH of the extracted process sample.
15. The method of claim 14, further comprising flushing water from the water source under control of the processor through the automated sampler and mixing chamber after step (f) to expel remnants of the diluted sample mixture therefrom in preparation for processing a subsequent sample.
16. An automated quantitative volumetric titration analyzer for performing automated quantitative volumetric titrations of a mineral slurry or process water in a vessel or passing through a conduit, the apparatus comprising: a processor operable to manage the operations associated with the apparatus; an automated sampler coupled to the vessel or conduit and operable to extract a sample of a determined volume of the slurry or process water from the vessel or conduit, the automated sampler being under control of the processor; a water source under control of the processor and operable to deliver a known volume of water into the sample; a titrant solution source under control of the processor and operable to deliver a known volume of titrant solution to the sample; a mixing chamber that receives the sample, the water, and the titrant solution; an agitator operable to agitate the sample, the water, and the titrant solution in the mixing chamber to produce a diluted sample mixture; an automated filter operable to extract an aliquot of the diluted sample mixture from the mixing chamber and to filter the aliquot to produce a filtrate; and a spectrophotometer having an optical flowcell that receives the filtrate from the automated filter and operable to measure a spectra absorbance of the filtrate in the optical flowcell using at least one wavelength to obtain spectra absorbance data of the filtrate.
17. The apparatus as claimed in claim 16, wherein the apparatus is online such that the sample is withdrawn from an online active process.
18. The apparatus as claimed in any one of claims 16-17, further comprising a source of chemicals under control of the processor and operable to deliver chemicals into the mixing chamber for chemically conditioning the sample mixture.
19. The apparatus as claimed in claim 18, further comprising a pH probe within the mixing chamber operable to measure a pH of the diluted sample mixture, wherein the processor is operable to control the delivery of chemicals to the sample mixture based on the pH measurement.
20. The apparatus as claimed in any one of claims 16-19, further comprising: a recirculating chiller coupled to the mixing chamber operable to heat or cool the sample mixture; a temperature probe in the mixing chamber operable to measure a temperature of the sample mixture; and wherein the processor is operable to receive the temperature measurement from the temperature probe and to activate the recirculating chiller based on the temperature measurement to achieve a desired temperature of the sample mixture.
21. The apparatus as claimed in any one of claims 16-20, wherein the processor is operable to instruct the automated sampler to extract the sample from the vessel or conduit.
22. The apparatus as claimed in any one of claims 16-21, wherein the water source delivers the known volume of water to the automated sampler after the sample has been extracted to flush the sample out of the automated sampler and into the mixing chamber.
23. The apparatus as claimed in any one of claims 16-22, wherein the processor is operable to instruct the water source to deliver the known volume of water to the automated sampler.
24. The apparatus as claimed in any one of claims 16-23, wherein the water source cooperates with the automated sampler to deliver the volume of water into the extracted sample to flush it out of the automated sampler to clean the automated sampler thereby ready it for obtaining a subsequent sample of slurry or process water.
25. The apparatus as claimed in any one of claims 16-24, wherein the agitator is controlled by the processor.
26. The apparatus as claimed in claim 25, wherein the processor is operable to activate the agitator to mix the sample mixture after the sample mixture is received in the mixing chamber.
27. The apparatus as claimed in any one of claims 16-26, wherein the water source is operable under control of the processor to flush water through one or both of the automated sampler and the mixing chamber to clean one or both of the automated sampler and the mixing chamber in preparation for processing a subsequent sample.
28. The apparatus as claimed in claim 27, wherein the processor is operable to activate the agitator while the water source is operable to flush water through the mixing chamber.
29. The apparatus as claimed in any one of claims 16-28, wherein the automated filter comprises: a second automated sampler coupled to the mixing chamber and operable to extract the aliquot from the mixing chamber after each delivery of the titrant solution; and a filter element downstream of the second automated sampler, wherein the second automated sampler pumps the aliquot through the filter element and the filtrate to the optical flowcell for obtaining spectra absorbance measurements of each filtrate.
30. The apparatus as claimed in claim 29, wherein the automated filter includes a pressure sensor that senses pressure of the aliquot upstream of the filter element; and a mechanism operable to replace the filter element with a fresh filter element as a result of a signal from the pressure sensor that the pressure of the aliquot has increased beyond a threshold pressure.
31. The apparatus as claimed in any one of claims 16-30, wherein the processor is operable to determine a titration endpoint from the spectra absorbance data.
32. The apparatus as claimed in any one of claims 16-31, wherein the processor is operable to control a processing of the mineral slurry or process water or to control in near real time a processing operation related to the mineral slurry or process water, based on the spectra absorbance data.
33. The apparatus as claimed in claim 32, wherein if the processor determines the titration endpoint has not been reached, the processor is further operable: to instruct the titrant solution source to deliver an additional known volume of titrant solution to the dilute sample mixture; thereafter to instruct the automated filter to obtain a subsequent aliquot of the diluted sample mixture and filter same to produce a subsequent filtrate; and thereafter to instruct the spectrophotometer to measure a spectra absorbance of the subsequent filtrate to obtain a subsequent spectra absorbance data; and thereafter determine if the titration endpoint has been reached from the subsequent spectra absorbance data.
34. The apparatus as claimed in claim 32, wherein if the processor determines the titration endpoint has been reached and/or enough titration data has been obtained, the processor is further operable to instruct the water source to flush water through one or both of the automated sampler and the mixing chamber to clean one or both of the automated sampler and the mixing chamber in preparation for processing a subsequent sample of mineral slurry or process water.
35. A method of automatically performing a quantitative volumetric titration on a mineral slurry or process water in a vessel or passing through a conduit, the method comprising the steps of: a. coupling an automated sampler with the vessel or conduit such that the automated sampler is operable to extract a sample of a known volume of the slurry or process water from the vessel or conduit; b. providing instructions from the processor to the automated sampler to extract the sample; c. flushing the sample from the automated sampler into a mixing chamber with a known volume of water from a water source under control of the processor; d. mixing the sample and water in the mixing chamber to produce a diluted sample mixture; e. adding a known volume of chemical and indicator solutions into the diluted sample mixture from chemical and indicator solution sources under control of the processor; f. adding a known volume of a titrant solution into the diluted sample mixture from a titrant solution source under control of the processor; g. filtering an aliquot of the diluted sample mixture through filter media of an automated filter and directing a filtrate of the aliquot into an optical flowcell of a spectrophotometer; h. measuring spectra absorbance of the filtrate under control of the processor to obtain spectra absorbance data of the filtrate, and storing the spectra absorbance data in memory; i. repeating steps (f) to (h) until a target spectra absorbance value or a plurality of target spectra absorbance values is reached to obtain a spectra absorbance data set; j. flushing water through the automated sampler and mixing chamber to expel remnants of the slurry sample and process solutions therefrom in preparation for processing a subsequent sample; and k. analyzing the spectra absorbance data set and using a result of the analysis in controlling processing of the mineral slurry or process water or controlling other aspects of a mineral processing operation related to the mineral slurry or process water.
36. The method as claimed in claim 35, further comprising a step of homogenizing the sample mixture before and after adding titrant solution to disperse particles in the sample mixture.
37. The method of claim 36, wherein the step of homogenizing the sample mixture takes place in the mixing chamber.
38. The method as claimed in any one of claims 35-37, further comprising a step of measuring a density of the slurry sample in the vessel or conduit near the analyzer.
39. The method as claimed in any one of claims 35-38, further comprising regulating a temperature of the sample mixture in the mixing chamber under control from the processor.
40. The method as claimed in claim 39 wherein the step of regulating a temperature of the diluted sample mixture comprises establishing a flow of hot fluid or cold fluid through a fluid jacket provided around at least a portion of the mixing chamber.
41. The method as claimed in any one of claims 35-40 further comprising repeating steps (b) to (j) to obtain a data set on a desired number of samples.
42. An automated liquid hardness analyzer for determining the hardness in a mineral slurry or process water in a vessel or passing through a conduit, the apparatus comprising: a processor operable to manage the operations associated with the apparatus; an automated sampler coupled to the vessel or conduit and operable to extract a sample of a determined volume of the slurry or process water from the vessel or conduit, the automated sampler being under control of the processor; a water source under control of the processor and operable to deliver a known volume of water into the sample; an Eriochrome Black T (EBT) solution source under control of the processor and operable to deliver a known volume of EBT solution to the sample; an Ethylenediamine Tetraacetic Acid (EDTA) solution source under control of the processor and operable to deliver a known volume of EDTA solution to the sample; a mixing chamber that receives the sample, the water, the EBT solution and the EDTA solution; an agitator operable to agitate the sample, the water, the EBT solution and the EDTA solution in the mixing chamber to produce a diluted sample mixture; an automated filter operable to extract an aliquot of the diluted sample mixture from the mixing chamber and to filter the aliquot to produce a filtrate; a spectrophotometer having an optical flowcell that receives the filtrate from the automated filter and operable to measure a spectra absorbance of the filtrate in the optical flowcell using at least one wavelength to obtain spectra absorbance data of the filtrate; and wherein the processor if operable to determine the EDTA titration endpoint from the spectra absorbance data and to correlate the EDTA titration endpoint and the cumulative EDTA solution volume to a liquid hardness value of the extracted sample.
43. The apparatus as claimed in claim 42, wherein the apparatus is online such that the sample is withdrawn from an online active process.
44. The apparatus as claimed in any one of claims 42-43, further comprising a source of chemicals under control of the processor and operable to deliver chemicals into the mixing chamber for chemically conditioning the sample mixture.
45. The apparatus as claimed in claim 44, further comprising a pH probe within the mixing chamber operable to measure a pH of the diluted sample mixture, wherein the processor is operable to control the delivery of chemicals to the sample mixture based on the pH measurement.
46. The apparatus as claimed in any one of claims further comprising: a recirculating chiller coupled to the mixing chamber operable to heat or cool the sample mixture; a temperature probe in the mixing chamber operable to measure a temperature of the sample mixture; and wherein the processor is operable to receive the temperature measurement from the temperature probe and to activate the recirculating chiller based on the temperature measurement to achieve a desired temperature of the sample mixture.
47. The apparatus as claimed in any one of claims 42-46, wherein the processor is operable to instruct the automated sampler to extract the sample from the vessel or conduit.
48. The apparatus as claimed in any one of claims 42-47, wherein the water source delivers the known volume of water to the automated sampler after the sample has been extracted to flush the sample out of the automated sampler and into the mixing chamber.
49. The apparatus as claimed in any one of claims 42-48, wherein the processor is operable to instruct the water source to deliver the known volume of water to the automated sampler.
50. The apparatus as claimed in any one of claims 42-49, wherein the water source cooperates with the automated sampler to deliver the volume of water into the extracted sample to flush it out of the automated sampler to clean the automated sampler thereby ready it for obtaining a subsequent sample of slurry or process water.
51. The apparatus as claimed in any one of claims 42-50, wherein the agitator is controlled by the processor.
52. The apparatus as claimed in claim 51, wherein the processor is operable to activate the agitator to mix the sample mixture after the sample mixture is received in the mixing chamber.
53. The apparatus as claimed in any one of claims 42-52, wherein the water source is operable under control of the processor to flush water through one or both of the automated sampler and the mixing chamber to clean one or both of the automated sampler and the mixing chamber in preparation for processing a subsequent sample.
54. The apparatus as claimed in claim 53, wherein the processor is operable to activate the agitator while the water source is operable to flush water through the mixing chamber.
55. The apparatus as claimed in any one of claims 42-54, wherein the automated filter comprises: a second automated sampler coupled to the mixing chamber and operable to extract the aliquot from the mixing chamber after each delivery of the EDTA solution; and a filter element downstream of the second automated sampler, wherein the second automated sampler pumps the aliquot through the filter element and the filtrate to the optical flowcell for obtaining spectra absorbance measurements of each filtrate.
56. The apparatus as claimed in claim 55, wherein the automated filter includes a pressure sensor that senses pressure of the aliquot upstream of the filter element; and a mechanism operable to replace the filter element with a fresh filter element as a result of a signal from the pressure sensor that the pressure of the aliquot has increased beyond a threshold pressure.
57. The apparatus as claimed in any one of claims 42-56, wherein the processor is operable to control a processing of the mineral slurry or process water in near real time based on the determined hardness value.
58. The apparatus as claimed in any one of claims 42-57, wherein if the processor determines the EDTA titration endpoint has not been reached, the processor is further operable: to instruct the EDTA solution source to deliver an additional known volume of EDTA solution to the dilute sample mixture; thereafter to instruct the automated filter to obtain a subsequent aliquot of the diluted sample mixture and filter same to produce a subsequent filtrate; and thereafter to instruct the spectrophotometer to measure a spectra absorbance of the subsequent filtrate to obtain a subsequent spectra absorbance data; and thereafter determine if the titration endpoint has been reached from the subsequent spectra absorbance data.
59. The apparatus as claimed in any one of claims 42-58, wherein if the processor determines the EDTA titration endpoint has been reached, the processor is further operable to instruct the water source to flush water through one or both of the automated sampler and the mixing chamber to clean one or both of the automated sampler and the mixing chamber in preparation for processing a subsequent sample of mineral slurry or process water.
60. A method of automatically determining a liquid hardness value of a mineral slurry or process water in a vessel or passing through a conduit, the method comprising the steps of: a. coupling an automated sampler with the vessel or conduit such that the automated sampler is operable to extract a sample of a known volume of the slurry or process water from the vessel or conduit; b. providing instructions from the processor to the automated sampler to extract the sample; c. flushing the sample from the automated sampler into a mixing chamber with a known volume of water from a water source under control of the processor; d. mixing the sample and water in the mixing chamber to produce a diluted sample mixture; e. adding known volume of chemical solutions into the diluted sample mixture from chemical solution source under control of the processor; f. adding a known volume of Eriochrome Black T (EBT) solution into the diluted sample mixture from an EBT solution source under control of the processor; g. adding a known volume of Ethylenediamine Tetraacetic Acid (EDTA) solution into the diluted sample mixture from an EDTA solution source under control of the processor; h. filtering an aliquot of the diluted sample mixture through filter media of an automated filter and directing a filtrate of the aliquot into an optical flowcell of a spectrophotometer; i. measuring spectra absorbance of the filtrate under control of the processor to obtain spectra absorbance data of the filtrate, and storing the spectra absorbance data in memory; j. repeating steps (g) to (i) until a target spectra absorbance value or a plurality of target spectra absorbance values is reached to obtain a spectra absorbance data set; k. flushing water through the automated sampler and mixing chamber to expel remnants of the sample and process solutions therefrom in preparation for processing a subsequent sample; and l. analyzing the spectra absorbance data set and using a result of the analysis in determining a liquid hardness value for the extracted sample.
61. The method as claimed in claim 60, further comprising a step of homogenizing the sample mixture before and after adding titrant solution to disperse particles in the sample mixture.
62. The method of claim 60, wherein the step of homogenizing the sample mixture takes place in the mixing chamber.
63. The method as claimed in any one of claims 60-62, further comprising a step of measuring a density of the slurry sample in the vessel or conduit near the analyzer.
64. The method as claimed in any one of claims 60-63, further comprising regulating a temperature of the sample mixture in the mixing chamber under control from the processor.
65. The method as claimed in claim 64 wherein the step of regulating a temperature of the diluted sample mixture comprises establishing a flow of hot fluid or cold fluid through a fluid jacket provided around at least a portion of the mixing chamber.
66. The method as claimed in any one of claims 60-65 further comprising repeating steps (b) to (j) to obtain a data set on a desired number of samples.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0096] In drawings which illustrate by way of example only embodiments of the invention:
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DETAILED DESCRIPTION
pH Analyzer:
[0121] In some embodiments, the present invention provides an automated and online mineral slurry and process water pH analyzer to determine liquid pH of mineral slurry or process water by withdrawing a controlled volume sample of slurry or process water from a live process, the process sample is mixed with a controlled volume and pH of dilution water in a mixing chamber, the pH of the diluted sample mixture is measured and correlated to determine the process sample's pH.
[0122] Referring to
[0123] pH analyzer 10 includes mixing chamber 40 that is downstream from and fluidly connected to the automated sampler 30. Mixing chamber 40 may include an agitator or mixer such as impeller 46 for thoroughly mixing the fluid sample. Other mixers and agitators may be used as would be apparent to a person skilled in the art in light of the present disclosure. The mixer or agitator is preferably coupled to and remotely actuatable by processor 70. Mixing chamber 40 receives the sample from the automated sampler 30 and mixes and disperses the sample by the impeller 46.
[0124] Online mineral slurry and process water pH analyzer 10 includes a source of water such as water container 31 that is fluidly connected to the automated sampler 30. The water source or water container 31 is operable to supply a controlled volume of water of a known pH to the automated sampler 30 to flush the slurry sample out of the automated sampler 30 and into the mixing chamber 40 and to dilute the sample. Preferably the water source such as water container 31 is coupled to and remotely actuatable and controlled by processor 70 to provide said controlled volume of water to the automated sampler 30.
[0125] Mixing chamber 40 includes a temperature probe to measure the temperature of the diluted sample solution. Mixing chamber 40 includes a thermal jacket connecting to a recirculating chiller operable to heat or cool the sample mixture to a desired temperature. Mixing chamber 40 includes a pH probe 48 for sensing the pH of the diluted sample mixture.
[0126] Online mineral slurry and process water pH analyzer 10 may include an automated filter 50 downstream of mixing chamber 40 and having porous filter element through which the diluted sample mixture is passed, after being processed in mixing chamber 40, to obtain the liquid analyte free of particles and hydrocarbon droplets. For example, porous filter element may comprise nylon membrane or other materials with pore size suitable for the mineral sample to be analyzed. The automated filter 50 is operable to remove coarse particulate and hydrocarbon droplets from the diluted sample mixture and allow the liquid filtrate to pass therethrough. An example of automated filter 50 may be a second ISOLOK™ automated sampler 51 of a style in which as a plunger of the sampler retracts, the front end of plunger collapses and generates pressure. This second ISOLOK automated sampler 51 may be coupled to the mixing chamber 40 so that it extracts an aliquot of the diluted sample mixture from the mixing chamber, and that is further coupled to one or more filter media or element 52. Once the aliquot of the diluted sample mixture is extracted from the mixing chamber, as the plunger of the sampler device retracts the front end of plunger collapses and generates pressure to propel the aliquot against a filter media to generate filtrate. The system may be configured to automatically replace the filter media with fresh filter media when it has become fouled. For example, automated filter may have an automated filter changer composed of multiple syringe filters 52, which connected to the outlet of the second ISOLOK™ automated sampler 51. When the processor 70 detects that the pressure resistance of the filter element has reached a threshold point due to fouling, it may provide instructions to the automated filter changer 52 to switch to a fresh filter element. While the foregoing is an example of an automated filter 50 and automated filter changer 52, other embodiments of an automated filter may be used that can extract multiple aliquots, filter them into filtrates. The pH of filtrate is measured by pH probe 49.
[0127] Online mineral slurry and process water pH analyzer 10 may include an oil skimming plate 41 installed in the mixing chamber 40 above the automated filter 50 to minimize oil or bitumen droplets entering the automated filter 50. A similar oil skimming plate may be provided above the pH probe 48 in the mixing chamber 40 to minimize oil or bitumen droplets from the sample attach to the pH probe 48.
[0128] pH probes 48 and 49 may be of a conventional type known in the art, such as for example a model PHCN-37 pH Controller and PHE-7352-15 pH probe manufactured and distributed by Omega. However, this example is for illustrative purposes and it would be apparent to a person skilled in the art in light of the present disclosure that other pH probes may be suitable for use as pH probes 48 and 49 in the present invention. pH probes 48 and 49 are coupled to processor 70 and provides the measured pH values to processor 70.
[0129] In operation, processor 70 instructs the automated sampler 30 to take a slurry or process water sample from a live pipeline or mixing vessel 20. Processor 70 then instructs the water source such as water container 31 to inject a controlled volume and known pH of dilution water into the automated sample 31 to flush the sample out of the automated sampler and thereby effect its dilution and transfer into the mixing chamber 40.
[0130] The processor 70 activates the mixer such as impeller 46 to disperse the diluted sample in the mixing chamber 40. After a predetermined time suitable for adequately dispersing the diluted sample, the processor 70 obtains a pH measurement of the diluted sample mixture from the pH probe 48.
[0131] In some aspects, processor 70 may instructs automated filter 50 to withdraw an aliquot of the dilute sample mixture. The withdrawn aliquot is filtered by automated filter 50 and the filtrate is measured by pH probe 49. Processor 70 may be operable to provide instructions to the automated filter 50. Processor 70 correlates the measured pH of the dilute sample mixture to the pH of process sample as further described herein. If the process sample is a slurry, the liquid content of the slurry is obtained from the slurry density measured by the densitometer installed near the pH analyzer.
[0132] The pH analyzer 10 provides a new pH measurement method and apparatus to determine process pH where direct measurement of pH from the process is not feasible due to hydrocarbons and abrasive solid particles contained in the process sample. This is achieved by obtaining a controlled volume of process sample, with an unknown pH, diluting it with a controlled volume of diluting water having a known pH, followed by measuring the pH of the diluted mixture. In some instances, the process sample may be diluted five or more times such that the hydrocarbons contained in the sample are much less likely to coat the pH probe 48 and solid particles in the diluted sample are much less likely to cause erosion as they are not flowing past the pH probe 48 at as high of a velocity in the mixing chamber as in the pipeline 20. In some instances, an aliquot of process sample may be extracted through the automated filter 50 to remove particles and hydrocarbons and the pH of filtrate is measured by the pH probe 49. In addition, the mixing chamber, pH probes and accessories are automatically cleaned after each measurement, there is no buildup of hydrocarbon coating on the pH probes. The pH of the extracted process sample can be calculated using the known volumes of liquid in the process sample, dilution water and diluted mixture, the known pH of the dilution water and the measured pH of the diluted sample mixture through [OH.sup.−] ion concentration conversion between diluted mixture, dilution water and process sample.
[0133] With reference to the numbered analysis steps in
[0137] In some instances and at step 4, an aliquot of the process sample in mixing chamber 40 is filtered by the automated filter 50 and the pH of filtrate is measured by the pH probe 49 and the measurement is communicated to the processor 70, which determines the pH of process sample. [0138] At step 5, after the sample pH value is determined, the processor 70 instructs the water container 31 to inject a volume of water into the mixing chamber via the automated sampler to flush the automated sampler 30 and the mixing chamber 40 to remove the spent slurry or process water. The processor causes a drainage port 53 at the bottom of mixing chamber 40 to open to allow the expulsion of the spent sample. The flushing water also cleans the automated sampler 30, the mixer 46 and pH probe 48, and the interior of the mixing chamber by engaging the mixer 46. Thereafter the pH analyzer 10 is ready to analyze the next sample.
[0139] The pH of diluted mixture as measured by pH probe 48 and/or pH probe 49 is correlated to the pH of process sample as follows.
[0140] pH is a measurement of acidity or alkalinity of a liquid solution, which is determined by the relative number of hydrogen ions [H.sup.+] and pOH is determined by hydroxyl ions [OH.sup.−] present in the solution. pH and pOH are defined by the following equations:
pH=−log.sub.10[H.sup.+] 1
pOH=−log.sub.10[OH.sup.−] 2
pH+pOH=14 3
[0141] The following equations can be derived from Equations 1 to 3:
[H.sup.+]=10.sup.−pH 4
[OH.sup.−]=10.sup.−pOH=10.sup.(pH−14) 5
[H.sup.+]+[OH.sup.−]=1×10.sup.−14 6
[0142] For a controlled volume of liquid sample withdraw from the process, its pH.sub.1 is unknown but can be determined from [OH.sup.−].sub.1 which has the unit of mol/L:
pH.sub.1=14−pOH.sub.1=14+log.sub.10[OH.sup.−].sub.1 7
V.sub.1=known volume 8
[0143] [OH.sup.−].sub.1 can be determined from the following procedures. By mixing a controlled volume V.sub.1 of process sample with a controlled volume of dilution water V.sub.2 at known pH.sub.2, the [OH.sup.−].sub.1 can be determined from pH.sub.2 using the following equations:
[OH.sup.−].sub.2=1×10.sup.(pH.sup.
V.sub.2=known volume 10
[0144] After mixing the process sample with the dilution water, the combined mixture pH.sub.3 can be measured and [OH].sub.3 is determined by:
[OH.sup.−].sub.3=1 ×10.sup.(pH.sup.
[0145] Therefore, the unknown pH.sub.1 can be solved from Equations 7 and 12, with conversions of [OH.sup.−] concentration from mol/L to mol using equation 13:
[OH.sup.−].sub.1=[OH.sup.−].sub.3−[OH.sup.−].sub.2 12
V.sub.3=V.sub.1+V.sub.2 13
[0146] There will be complications from buffering effect of other ions present in the process sample and effects such as temperatures, but these effects can be pre-determined through calibration.
Example 1
[0147] Four oil sands tailings samples were tested using an automated and on-line pH analyzer described herein. The process sample volume V.sub.1, dilution water volume V.sub.2 and the dilution water pH.sub.2 are controlled; the combined mixture volume V.sub.3 are known; the combined mixture pH.sub.3 is measured by pH probe 48. The process sample pH.sub.1 can be correlated from the controlled and measured values. The difference between correlated pH.sub.1 and the actual pH.sub.1 is within 10% for the four oil sands tailings samples. The difference can be further reduced through equipment and procedure optimizations.
TABLE-US-00001 TABLE 1 Examples of On-line pH Meter Measurements on Oil Sands Process Water Samples Measured Difference Oil Sands Dilution Water Combined Mixture Correlated Process Sample Process Correl. Sample V.sub.1 pH.sub.2 V.sub.2 [OH.sup.−].sub.2 pH.sub.3 V.sub.3 [OH.sup.−].sub.3 [OH.sup.−].sub.1 [OH.sup.−].sub.1 pH.sub.1 pH.sub.1 vs. Meas. (mL) (pH) (mL) (mol) (pH) (mL) (mol) (mol) (mol/L) (pH) (pH) (%) 5.30 6.38 449.7 1.08E−08 7.28 455.0 8.67E−08 7.59E−08 1.43E−05 9.16 8.84 3.6 15.80 6.38 449.6 1.08E−08 7.80 465.4 2.94E−07 2.83E−07 1.79E−05 9.25 8.86 4.4 5.50 6.38 199.9 4.79E−09 7.70 205.4 1.03E−07 9.81E−08 1.78E−05 9.25 8.79 5.2 16.20 6.38 200.0 4.80E−09 7.90 216.2 1.72E−07 1.67E−07 1.03E−05 9.01 8.67 4.0
[0148] Some general implementations of the present invention may be in applications where direct measurement of pH from process fluid is not feasible, such as for example when hydrocarbons in the fluid may interfere the reading or even coat the pH probe and make the measurement inaccurate or impossible, and/or when solid particles in the slurry would be abrasive to the surface of pH that damage the probe in a short time.
[0149] Quantitative Volumetric Titrations
[0150] In some embodiments, the present invention provides an automated online mineral slurry and process water quantitative volumetric titration analyzer that automatically performs titrations on a sample of mineral slurry or process water and determines an endpoint of the titration based on changes in liquid spectra and correlates the endpoint to the cumulative titrant volume and one or more parameters of the mineral slurry or process water. A controlled volume of mineral slurry or process water sample is automatically withdrawn from the process and mixed with dilution water at controlled volume. The diluted mixture sample is then conditioned with chemicals and indicator and/or has its temperature regulated, as required by the titration protocol, followed by injecting in increments a controlled volume of a titrant solution. After each titrant solution injection, a filtrate is extracted from the mixture. The filtrate spectra absorbance is measured by a spectrophotometer and correlated to the cumulative volume of titrant solution and/or a parameter of the mineral slurry or process water.
[0151] Referring to
[0152] Quantitative volumetric titration analyzer 110 includes automated sampler 130 that is operably mounted on a mineral slurry or process water pipeline, vessel, tank or conduit, such as pipeline 120, to withdraw a sample of the slurry or process water from the flow without interfering with the operation of the pipeline or conduit. The automated sampler 130 withdraws a controlled volume of the slurry or process water and transfers it to mixing chamber 140. An example of a suitable automated sampler 130 is an ISOLOK™ automated sampler produced and distributed by Sentry Equipment of Oconomowoc, WI, USA; however, other automated samplers may be suitable for use as automated sampler 130 as would be apparent to persons skilled in the art in light of the present disclosure. For example, some automated wall samplers or isokinetic samplers may be suitable. The automated sampler is preferably coupled to and remotely actuatable and controlled by a computer, processor or other controller, herein referred to generally as processor 170.
[0153] The volumetric titration analyzer 110 includes mixing chamber 140 that is downstream from and fluidly connected to the automated sampler 130. Mixing chamber 140 may include an agitator or mixer such as impeller 146 for thoroughly mixing the fluid sample. Other mixers and agitators may be used as would be apparent to a person skilled in the art. The mixer or agitator is preferably coupled to and remotely actuatable by processor 170. Mixing chamber 140 receives the sample from the automated sampler 130 and mixes and disperses the sample by impeller 146.
[0154] Volumetric titration analyzer 110 includes a source of water such as water container 131 that is fluidly connected to the automated sampler 130. The water source or water container 131 is operable to supply a controlled volume of water to the automated sampler 130 to flush the slurry sample out of the automated sampler 130 and into the mixing chamber 140 and to dilute the sample. Preferably the water source 131 is coupled to and remotely actuatable and controlled by processor 170 to provide said controlled volume of water to the automated sampler 130.
[0155] Volumetric titration analyzer 110 includes one or more sources of chemicals such as chemicals containers 133 and 134 that are fluidly connected to the mixing chamber 140. The source of chemicals is operable to supply a controlled volume of chemicals to the mixing chamber 140. Preferably the source of chemicals such as chemicals containers 133 and 134 are coupled to and remotely actuatable and controlled by the processor 170 to provide said controlled volume of chemicals to the mixing chamber 140. Processor 170 instructs the source of chemicals such as chemicals containers 133 and 134 to inject a controlled volume of chemicals into the mixing chamber 140. The processor 170 instructs the mixer such as impeller 146 to disperse the diluted sample in the mixing chamber 140 to produce a diluted conditioned sample mixture.
[0156] The chemicals used in the process will vary depending on operational factors, including but not limited to the particular protocol for the volumetric titration being used, the source of the mineral slurry, and the kinds of chemicals used and quantities would be apparent to those skilled in the specific field. By way of example only, the chemicals may include acids, bases or buffers to adjust the pH of the sample, and/or chemicals to remove hydrocarbons from the slurry or process water sample, and/or chemical indicator for complexometric titration.
[0157] Mixing chamber 140 may include a temperature probe to measure the temperature of the diluted sample solution. Mixing chamber 140 may include a thermal jacket connecting to a recirculating chiller operable to heat or cool the sample mixture to a desired temperature. The temperature probe and the recirculating chiller may be each coupled to the processor 170 which is operable to compare a measured temperature value from the temperature probe to a desired temperature for the titration protocol, and to activate the recirculating chiller as required to achieve the desired temperature in the sample mixture.
[0158] Mixing chamber 140 may include a pH probe 148 for sensing a pH of the sample mixture. The pH probe 148 may be coupled to the processor 170 to provide measured values to the processor. The processor 170 may be operable to compare a measured pH value from the pH probe 148 to a desired pH value for the titration, and to activate the chemical containers 133 and/or 134 to dispense a volume of chemicals into the sample solution to achieve the desired pH value. Hence the pH probe 148 may be coupled to a feedback mechanism for regulating the volume of chemicals dispensed into the mixing chamber 140 from the source of chemicals.
[0159] Volumetric titration analyzer 110 includes a source of titrant solution such as titrant solution container 137 that is fluidly connected to the mixing chamber 140 to supply a controlled volume of the titrant solution to the mixing chamber 140. Preferably the source of titrant such as titrant solution container 137 is coupled to and remotely actuatable and controlled by the processor 170 to provide said controlled volume of titrant to the mixing chamber 140. Processor 170 instructs the source of titrant solution such as titrant solution container 137 to inject a controlled volume of titrant solution into the mixing chamber 140 at multiple times.
[0160] The titrant solution used in a quantitative volumetric titration is one that binds to a specific target compound in the diluted sample mixture to effect a change in the intensity and/or the color of the solution, and which change can be measure by a spectrophotometer. Examples of titrants include, but are not limited to: [0161] Methylene blue (MB) as an indicator for determining the methylene blue index (MBI) value and active clay content of mineral and mineral slurry. [0162] Phthalein Purple for determining Calcium and/or Magnesium ions at two distinctive pH ranges in a mineral slurry or process water, and/or vice versa to determine sample pH if the Calcium and/or Magnesium content in the sample is known. [0163] A specific complexometric titration using Ethylenediamine Tetraacetic Acid (EDTA) as titrant for determining the total liquid hardness (Calcium and Magnesium combined) and/or liquid hardness contributed by Calcium or Magnesium individually of the sample slurry or process water. [0164] Any type of Complexometric Titration that a colored complex is formed during the titration such that the endpoint of the volumetric titration is indicated by the liquid color change which can be detected by a spectrophotometer, the complexometric titration endpoint can be determined and quantified by correlating the liquid spectra absorbance and the cumulative volume of the titrant solution.
[0165] A person skilled in the art, in light of the present disclosure, would understand that other titrants may be used with the quantitative volumetric titration analyzer of the present invention to determine a parameter of the mineral slurry or process water for which such titrant is suitable using titration techniques.
[0166] Accordingly, mixing chamber 140 is operable to receive the diluted sample from the automated sampler 130, a controlled volume of chemicals from the chemicals containers 133 and 134, controlled volumes of titrant solution from the titrant solution container 137, and to thoroughly mix these compounds into a diluted sample mixture.
[0167] Volumetric titration analyzer 110 includes an automated filter 150 downstream of mixing chamber 140 and having porous filter element through which the diluted sample mixture is passed, after being processed in mixing chamber 140, to obtain the liquid analyte. For example, porous filter element may comprise nylon membrane or other materials with pore size suitable for the mineral sample to be analyzed. The automated filter 150 is operable to remove coarse particulate and hydrocarbon droplets from the diluted sample mixture and allow the liquid filtrate to pass therethrough. An example of automated filter 150 may be a second ISOLOK™ automated sampler 151 of a style in which as a plunger of the sampler retracts, the front end of plunger collapses and generates pressure. This second ISOLOK automated sampler 151 may be coupled to the mixing chamber 140 so that it extracts an aliquot of the chemically treated and diluted sample mixture from the mixing chamber, and that is further coupled to a filter changer 152. Once the aliquot of the chemically treated sample mixture is extracted from the mixing chamber, the plunger of the sampler device retracts that the front end of plunger collapses and generates pressure to propel the aliquot against a filter media to generate filtrate. The system may be configured to automatically replace the filter media with fresh filter media when it has become fouled. For example, the automated filter changer 152 connects to the outlet of the second ISOLOK™ automated sampler 151. When the processor 170 detects that the pressure resistance of filter element has reached a threshold point due to fouling, it may provide instructions to the automated filter changer 152 to switch to a fresh filter element. While the foregoing is an example of an automated filter 150, other embodiments of an automated filter may be used that can extract multiple aliquots, filter them into filtrates and convey the filtrates to the spectrophotometer.
[0168] Volumetric titration analyzer 110 may include an oil skimming plate 141 installed in the mixing chamber 140 above the automated filter 150 to minimize oil or bitumen droplets entering the automated filter 150. A similar oil skimming plate may be provided above the pH probe 148 in the mixing chamber 140 to minimize oil or bitumen droplets from the sample attach to the pH probe 148.
[0169] Volumetric titration analyzer 110 includes a spectrophotometer 160 having an optical flowcell that receives the filtrate from the automated filter 150. Spectrophotometer 160 is operable to measure the spectra absorbance of the filtrate in the flowcell at pre-calibrated range of wavelengths, and the spectra absorbance is transmitted to processor 170 for computational analysis. A suitable spectrophotometer 160 for use in the present invention includes but is not limited to a Model CXR-25 Black Comet Spectrophotometer manufactured by Stellar Net USA. A suitable flowcell for use in the present invention includes but is not limited to a Model RK-83057-79 manufactured by Cole-Parmer. The spectra absorbance data is used by the processor 170 to determine a parameter of the slurry or process water sample, which may be used on its own or in conjunction with other parameters to control the process either upstream or downstream of the automated sampler 130.
[0170] Accordingly, the diluted sample mixture in the mixing chamber 140 is conditioned with chemicals from the chemical containers 133 and 134 until, for example, the diluted sample mixture reaches a target pH as measured by the pH probe 148. While mixing, a controlled volume of titrant solution is injected in increments under the control of processor 170 into the sample mixture from the titrant solution container 137. After each titrant solution injection, a small aliquot of the sample mixture is withdrawn from the mixing chamber through automated filter 150. Processor 170 instructs automated filter 150 to withdraw an aliquot of the dilute sample mixture after an injection of the titrant solution and once sufficient time has elapsed to enable thorough mixing of the sample mixture and titrant. The withdrawn aliquot is filtered by automated filter 150 and the filtrate is transferred, as a result of pressure generated by the automated filter 150 or by a peristatic pump, to the spectrophotometer 160 via an optical flowcell where the spectra absorbance of the filtrate is measured. Processor 170 may be operable to provide instructions to the automated filter 150. Processor 170 may be coupled to the spectrophotometer 160 to receive spectra absorbance measurements and to store such data in memory. Processor 170 may be operable to analyze the stored spectra data to determine a titration endpoint, and to correlate the titration endpoint and the cumulative titrant volume injected with the desired parameter to be determined for the sample.
[0171] The injection of titrant solution and the spectra absorbance measurement of each aliquot taken after each such titrant solution injection continues until the processor determines that the measured spectra absorbance data indicates that an endpoint in the titration has been reached or passed, which indicates total reaction of the titrant solution with the target ion(s) in the liquid from which a desired parameter of the liquid may be determined, or until enough spectra absorbance data is obtained to be useful in deriving a desired parameter of the sample. The spectra absorbance and the cumulative titrant solution volume injected can be correlated by the processor to determine the desired parameter, which can be used to achieve effective process control and management.
[0172] More specifically, with reference to the numbered analysis steps in
[0187] Volumetric titration analyzer 110 provides a new method and apparatus that utilizes a spectrophotometer to automatically determine a titration endpoint as a replacement of a conventional titration procedure. This is achieved by a series of online and automated procedures, including automated withdrawal of samples from a live process, condition the sample in a mixing chamber, incrementally adding a controlled volume of the titrant solution, extracting a filtrate by an automated filter, measuring the filtrate spectra absorbance by a spectrometer, and using the spectra absorbance measurements to determine when an endpoint of the titration has been reached and correlating the spectra absorbance data with cumulative titrant solution volume injected to reach the titration endpoint to determine a parameter of the mineral slurry or process water. The volumetric titration analyzer can be used automatically and continuously, and it improves the accuracy by eliminating human subjective and visual endpoint detection. Furthermore, the spectra absorbance data, even before reaching the endpoint, can be used for correlation and process control, which can replace or supplement the endpoint detection and shorten the measuring time.
[0188] In an embodiment, the quantitative volumetric titration analyzer of the present invention is configured to determine the active clay content of a mineral slurry sample. The titrant solution is methylene blue (MB). At step 109, the absorbance spectra measured by the spectrophotometer 160 is analyzed by the processor 170 to determine a titration endpoint. The volume of MB solution used to reach the titration endpoint, along with normality (concentration) of the MB solution and sample mass, can be used to determine methylene blue index (MBI) value of the mineral sample based on the following known equation:
[0189] Where: [0190] MBI=methylene blue index for the mineral sample in meq/100 g; [0191] E=milliequivalents of methylene blue per millilitre; [0192] V=millilitres of methylene blue solution required for the titration; and [0193] W=grams of mineral sample, dry basis.
[0194] There are many empirical MBI equations derived from Equation 14 to be applied for specific minerals such as, for example, oil sands tailings.
[0195] Referring to
[0196] Water Hardness:
[0197] In some embodiments, the present invention provides an automated and online mineral slurry and process water hardness analyzer to determine the hardness of a mineral slurry or process water by withdrawing a controlled volume of slurry or process water sample from a live process, the process sample is mixed with a controlled volume of dilution water in a mixing chamber, the pH of the diluted mixture is measured. The diluted mixture is conditioned with chemicals to reach a target pH. A controlled dose of water hardness indicator such as Eriochrome Black T (EBT) is injected into the mixture, followed by injecting water hardness titrant such as Ethylenediamine Tetraacetate Acid (EDTA) in increments; at each EDTA injection, a filtrate is extracted from the mixture and analyzed by a spectrophotometer. The filtrate's spectra absorbance is used to determine the EDTA titration endpoint and correlate to the hardness of liquid. The analyzer can be installed on a live slurry conduit or water supply line and can automatically and continuously take and analyze slurry or process water samples.
[0198] Referring to
[0199] Liquid hardness analyzer 210 includes automated sampler 230 that is operably mounted on a mineral slurry or process water pipeline, vessel, tank or conduit, such as pipeline 220, to withdraw a sample of the slurry or process water from the flow without interfering with the operation of the pipeline or conduit. The automated sampler 230 withdraws a set volume of the slurry or process water and transfers it to mixing chamber 240. The automated sampler is preferably remotely actuatable and controlled by a computer or other programmable controller. An example of a suitable automated sampler 230 is an ISOLOK™ automated sampler produced and distributed by Sentry Equipment of Oconomowoc, WI, USA; however, other automated samplers may be suitable for use as automated sampler 230 used as would be apparent to persons skilled in the art in light of the present disclosure. For example, some automated wall samplers or isokinetic samplers may be suitable. The automated sampler is preferably coupled to and remotely actuatable and controlled by a computer, processor, or other controller, herein referred to generally as processor 270.
[0200] Liquid hardness analyzer 210 includes mixing chamber 240 that is downstream from and fluidly connected to the automated sampler 230. Mixing chamber 240 may include an agitator such as impeller 246 for thoroughly mixing the fluid sample. Other mixers and agitators may be used as would be apparent to a person skilled in the art. The agitator or agitators are preferably remotely actuatable and controlled by a computer or other programmable controller. Mixing chamber 240 receives the slurry sample from the automated sampler 230 and mixes and disperses the sample.
[0201] Liquid hardness analyzer 210 includes a source of water such as water container 231 that is fluidly connected to the automated sampler 230. The water source is operable to supply a controlled volume of water to the automated sampler 230 to flush the slurry sample out of the automated sampler 230 and into the mixing chamber 240 and to dilute the sample. Preferably the water source is remotely actuatable and controlled by a computer or other programmable controller to provide said controlled volume of water to the automated sampler 230.
[0202] Liquid hardness analyzer 210 includes one or more sources of chemicals such as chemicals containers 233 and 234 that are fluidly connected to the mixing chamber 240. The source of chemicals is operable to supply a controlled volume of chemicals to the mixing chamber 240. Preferably the source of chemicals is remotely actuatable and controlled by a computer or other programmable controller to provide said controlled volume of chemicals to the mixing chamber 240. The chemicals used in the process will vary depending on operational factors, including but not limited to the source of the mineral slurry, and the kinds of chemicals used and quantities would be apparent to those skilled in the specific field. By way of example only, the chemicals may include acids, bases or buffers to adjust the pH of the sample, and/or chemicals to remove hydrocarbons from the slurry or process water sample.
[0203] Liquid hardness analyzer 210 includes a source of water hardness indicator that is fluidly connected to the mixing chamber 240 to supply a controlled volume of the indicator to the mixing chamber 240. Preferably the source of indicator is remotely actuatable and controlled by a computer or other programmable controller to provide said controlled volume of indicator to the mixing chamber 240. A preferred water hardness indicator is Eriochrome Black T (EBT), or other liquid hardness indicators such as hydroxy naphthol blue, and an example of a source of indicator is EBT container 235 (
[0204] Liquid hardness analyzer 210 also includes a source of water hardness measurement solution that is fluidly connected to the mixing chamber 240 to supply a controlled volume of measurement solution to the mixing chamber 240. Preferably the source of measurement solution is remotely actuatable and controlled by a computer or other programmable controller to provide said controlled volume of measurement solution to the mixing chamber 240. A preferred water hardness titrant is Ethylenediamine Tetraacetate Acid (EDTA), or other water hardness titrant such as Phthalein Purple, and an example of a source of titrant is EDTA container 237 (
[0205] Accordingly, mixing chamber 240 is operable to receive the diluted slurry sample from the automated sampler 230, a controlled volume of chemicals from the chemicals containers 233 and 234, a controlled volume of liquid hardness indicator EBT from the EBT container 235, a controlled and increment volume of liquid hardness titrant solution EDTA from the EDTA container 237, and thoroughly mix these compounds into a sample mixture.
[0206] In some embodiments, mixing chamber 240 may include a temperature probe to measure the temperature of the diluted sample solution. Mixing chamber 240 may include a thermal jacket connecting to a recirculating chiller operable to heat or cool the sample mixture to a desired temperature. In some embodiments, mixing chamber 240 includes a pH probe 248 for sensing the pH of the sample mixture, and the pH probe 248 may be coupled to a feedback mechanism for regulating the volume of chemicals dispersed into the mixing chamber 240 from the source of chemicals.
[0207] Liquid hardness analyzer 210 includes an automated filter 250 downstream of mixing chamber 240 and having porous filter element through which the diluted sample mixture is passed, after being processed in mixing chamber 240, to obtain the liquid analyte. For example, porous filter element may comprise nylon membrane or other materials with pore size suitable for the mineral sample to be analyzed. For example, the filter pore sizes may be in the range of 0.1 μm to 3.0 μm.
[0208] The automated filter 250 is operable to remove coarse particulate and hydrocarbon droplets from the diluted sample mixture and allow the liquid filtrate to pass therethrough. An example of automated filter 250 may be a second ISOLOK™ automated sampler 251 of a style in which as a plunger of the sampler retracts, the front end of plunger collapses and generates pressure. This second ISOLOK™ automated sampler 251 may be coupled to the mixing chamber 240 so that it extracts an aliquot of the diluted sample mixture from the mixing chamber, and that is further coupled to an automated filter changer 252. Once the aliquot of the diluted sample mixture is extracted from the mixing chamber, the plunger of the sampler device retracts that the front end of plunger collapses and generates pressure to propel the aliquot against a filter media to generate particle free filtrate. The system may be configured to automatically replace the filter media with fresh filter media when it has become fouled. For example, the automated filter changer 252 connects to the outlet of the second ISOLOK™ automated sampler 251. When the processor 270 detects that the pressure resistance of filter element has reached a threshold point due to fouling, it may provide instructions to the automated filter changer 252 to switch to a fresh filter element. While the foregoing is an example of an automated filter 250, other embodiments of an automated filter feeding mechanisms may be used that can extract multiple aliquots, filter them into filtrates and convey the filtrates to the spectrophotometer.
[0209] Liquid hardness analyzer 210 may include an oil skimming plate 241 installed in the mixing chamber 240 above the automated filter 250 to minimize oil or bitumen droplets enter the automated filter 250. A similar oil skimming plate may be installed above the pH probe 248 in the mixing chamber 240 to minimize oil or bitumen droplets in the sample attach to the pH probe 248.
[0210] Liquid hardness analyzer 210 includes spectrophotometer 260 having an optical flowcell that receives the filtrate from the automated filter 250. Spectrophotometer 260 is operable to measure the spectra absorbance of the filtrate in the flowcell at pre-calibrated range of wavelengths, and the spectra absorbance is transmitted to processor 270 for computational analysis. A suitable spectrophotometer 260 for use in the present invention includes but is not limited to a Model CXR-25 Black Comet Spectrophotometer manufactured by Stellar Net USA. A suitable flowcell for use in the present invention includes but is not limited to a Model RK-83057-79 manufactured by Cole-Parmer. The spectra absorbance data is used to determine liquid hardness of the slurry or process water sample, which may be used on its own or in conjunction with other parameters to control water heating equipment such as boilers and the associated process.
[0211] Accordingly, the diluted mixture in the mixing chamber 240 is conditioned with chemicals from the chemical containers 233 and 234 and EBT from EBT container 235 until, for example, the diluted mixture reaches a target pH as measured by the pH probe 248. While mixing, EDTA solution is injected in increments into the sample mixture from the EDTA container 237. After each EDTA injection and dispersing, a small aliquot of the sample is withdrawn from the mixing chamber through automated filter 250. The filtrate is transferred by the pressure from automated filter 250 or by a peristatic pump to the spectrophotometer 260 via an optical flowcell where the spectra absorbance of the filtrate is measured.
[0212] Processor 270 may be operable to provide instructions to the automated filter 250. Processor 270 may be coupled to the spectrophotometer 260 to receive spectra absorbance measurements and to store such data in memory. Processor 270 may be operable to analyze the stored spectra data to determine a titration endpoint, and to correlate the titration endpoint with the desired parameter to be determined for the sample.
[0213] The injection of EDTA solution and the spectra absorbance measurement of each aliquot taken after each such EDTA injection will continue until the measured spectra absorbance indicates that an endpoint has been reached or passed, which indicates total reaction of EDTA with Calcium and Magnesium ions in the liquid and a liquid hardness can be determined, or until enough spectra absorbance data is obtained to be useful in deriving a liquid hardness. The spectra absorbance and the cumulative EDTA volume injected can be correlated to determine the liquid hardness, so to achieve effective process control and water management.
[0214] More specifically, with reference to the numbered analysis steps in
[0228] According to ASTM D1126-17, the hardness of water can be determined using the following equation:
Hardness,epm=20 C/S 15
[0229] Where [0230] epm=equivalent parts per million; milliequivalents per litre [0231] C=standard Na.sub.2H.sub.2EDTA solution added in titrating hardness, mL, and [0232] S=sample volume, mL
[0233] Other types of water hardnesses, such as Calcium hardness, Magnesium hardness and hardness as Calcium Carbonate use the similar calculation as the hardness of water, the key is to obtain the volume of standard Na.sub.2H.sub.2EDTA (a.k.a. EDTA) added into the liquid sample when reaching the titration endpoint; or in other words when Calcium and Magnesium ions are fully un-complexed with the EBT by the addition of EDTA.
[0234] In the online mineral slurry and process water hardness analyzer of the present invention, the endpoint is determined by correlating the spectra absorbance vs. EDTA volume titrated into the sample, as shown in
Example 2
[0235] An oil sands SAGD process water is tested using the automated and on-line liquid hardness analyzer as described herein.
[0236] Liquid hardness analyzer 210 provides a new liquid hardness method and apparatus that utilizes a spectrophotometer to determine the titration endpoint as a replacement of the conventional titration procedures outlined by ASTM D1126-17. This is achieved by a series of online and automated procedures, including automated withdraw of sample from a process, condition it in a mixing chamber, extract a filtrate by an automated filter and analyze it by a spectrometer, then correlate the filtrate spectra absorbance with cumulative EDTA volume injected until reach the titration endpoint. The analyzer can be used automatically and continuously, and it improves the accuracy by eliminating human subjective and visual endpoint detection as shown in
[0237] The present invention also provides close to real-time measurement of total hardness, Calcium and Magnesium hardness, the liquid hardness as Calcium Carbonate, Calcium and Magnesium ion concentration etc., this enables automated and online monitoring of process pH and hardness in liquid of slurry or process water.
[0238] Some general implementations of the present invention may be as follows:
[0239] Applications where an online measurement of hardness in water is required to monitor the quality of water supply to heating equipment such as boiler and heat exchanger. The current ICP method requires delicate instrumentations and well trained personnel to operate, the requirement for sample is very high that it need considerable time to process and to prepare the sample, such that it cannot be converted into an automated and online method; the ICP is also not suitable to be operated near or at the process sites as it is not robust enough to be developed as an online method as it cannot be accommodated to harsh process conditions such as high temperature, high pressure and dusty environment.
[0240] While embodiments of the invention have been described and illustrated, such embodiments should be considered illustrative of the invention only. The invention may include variants not described or illustrated herein in detail. Thus, the embodiments described and illustrated herein should not be considered to limit the invention.