TREATMENT OF SLUDGES AND FLOCCULANTS USING INSOLUBLE MINERAL COLLOIDAL SUSPENSIONS

Abstract

A method of separating sludges which involves adding an insoluble mineral colloidal suspension into an industrial sludge to destabilize the industrial sludge and separating destabilized components of the industrial sludge. The insoluble mineral colloidal suspension can be adding into the industrial sludge or formed in situ therein by components into the industrial sludge that react together therein to form the insoluble mineral colloidal suspension.

Claims

1. A method of separating sludges which comprises: obtaining an industrial sludge, wherein the industrial sludge comprises wastewater sludge, refinery sludge, sludge from DNF processes, sludge from DAF processes, sludge from API separators, or tank clean-out sludge; adding an insoluble mineral colloidal suspension into the industrial sludge to destabilize the industrial sludge; and separating destabilized components of the industrial sludge.

2. A method of separating sludges according to claim 1, wherein a flocculant and/or coagulant is added to the industrial sludge to aid in the separation of the destabilized components of the industrial sludge.

3. A method of separating sludges according to claim 1, wherein the insoluble mineral colloidal suspension is added into the industrial sludge by forming the insoluble mineral colloidal in situ in the industrial sludge.

4. (canceled)

5. (canceled)

6. A method of separating sludges according to claim 1, wherein the industrial sludge is a combined bottom sludge and top float.

7. A method of separating sludges according to claim 1, wherein the insoluble mineral colloidal suspension is formed in situ in the industrial sludge by adding components into the industrial sludge that react together therein to form the insoluble mineral colloidal suspension.

8. A method of separating sludges according to claim 1, wherein the insoluble mineral colloidal suspension has a solids percent by weight of at least 25%.

9. A method of separating sludges according to claim 8, wherein the insoluble mineral colloidal suspension has a solids percent of up to 65%.

10. A method of separating sludges according to claim 9, wherein the insoluble mineral colloidal suspension has a solids percent by weight that ranges from 25% to 65%.

11. A method of separating sludges according to claim 1, wherein the insoluble mineral colloidal suspension comprises an alkaline earth salt.

12. A method of separating sludges according to claim 11, wherein the insoluble mineral colloidal suspension comprises a calcium salt.

13. A method of separating sludges according to claim 1, wherein the insoluble mineral colloidal suspension comprises an iron hydroxide.

14. A method of separating sludges according to claim 1, wherein the insoluble mineral colloidal suspension comprises insoluble precipitates from a lime softening water treatment process.

15. A process for physically separating components of a sludge wherein the sludge comprises wastewater sludge, refinery sludge, sludge from DNF processes, sludge from DAF processes, sludge from API separators, or tank clean-out sludge, the improvement comprising adding insoluble mineral colloidal suspension into the sludge prior to physically separating components of the sludge.

16. A process for physically separating components of a sludge according to claim 15, wherein the process for physically separating the components of the sludge includes at least one of gas-assisted flotation, gravity separation and centrifugal separation.

17. A process for physically separating components of a sludge according to claim 16, wherein the process for physically separating the components of the sludge comprises one of dissolved nitrogen floatation and dissolved air flotation.

18. A process for physically separating components of a sludge according to claim 16, wherein the process for physically separating the components of the sludge comprises the use of an American Petroleum Institute Separator.

19. A process for physically separating components of a sludge according to claim 9, wherein the insoluble mineral colloidal suspension has a solids percent by weight of at least 25%.

20. A process for physically separating components of a sludge according to claim 9, wherein the insoluble mineral colloidal suspension has a solids percent of up to 65%.

21. A method of separating sludges according to claim 1, the method further comprising heating the industrial sludge and insoluble mineral colloidal suspension to 170 F.

22. The method of separating sludges according to claim 21, wherein the industrial sludge and insoluble mineral colloidal suspension are heated from ambient temperature to 170 F.

23. A method of separating sludges according to claim 1, the method further comprising addition of sulfuric acid to the industrial sludge and insoluble mineral colloidal suspension to adjust pH to 7-11.

24. A method of separating sludges according to claim 1, the method further comprising adjusting the pH of the insoluble mineral colloidal suspension to 7-11 prior to adding the insoluble mineral colloidal suspension into the industrial sludge.

Description

DETAILED DESCRIPTION OF THE DRAWINGS AND THE PRESENTLY PREFERRED EMBODIMENTS

[0021] The present invention relates generally to separating sludges and more particularly to the addition of insoluble mineral colloidal suspensions to DNF, DAF, and API sludges, and other sludge wastes for purposes of separation and component recovery.

[0022] The insoluble colloidal mineral suspension used in the present invention can be added to the sludges and/or floats or can be generated in situ by forming the insoluble colloidal mineral suspension from a multi-component mixture that is added to the sludges and reacts to produce the insoluble mineral colloidal suspensions in situ. In further embodiments of the present invention certain waste streams yielding precipitated suspensions of insoluble minerals have also proven effective. For example, the slurry formed by concentrating the solids from lime softening of hard water results in a suspension suitable for use in the disclosed invention. Those familiar with the art will understand the benefits of using these materials to destabilize various types of sludge including DNF, DAF, API, and other sludge and/or float wastes.

[0023] Adding an insoluble colloidal mineral suspension into an industrial sludge directly or forming the insoluble colloidal mineral suspension in situ in an industrial sludge according to the present invention causes colloidal particles and very fine solid suspensions initially present in the industrial sludge to combine into larger agglomerates that can be separated by means of sedimentation, flocculation, filtration, centrifugation, or other separatory methods.

[0024] The insoluble colloidal mineral suspensions of the present invention can include alkaline earth salt precipitates such as calcium sulfate and barium sulfate which can be added into an industrial sludge or formed therein by reacting alkaline earth metals with sulfuric acid to form the corresponding salts.

[0025] In other embodiments a source of iron such as ferric chloride or ferrous chloride are reacted with hydroxide ions (from a soluble alkali hydroxide or alkaline hydroxide) to form insoluble iron hydroxides.

[0026] In further embodiments soluble salts such as calcium chloride and be reacted with sulfates or carbonates such as magnesium or sodium sulfate or sodium carbonate to form insoluble calcium salts including calcium sulfate and calcium carbonate.

[0027] The insoluble colloidal mineral suspensions can have percent solids deemed sufficient to allow material management, such as pumpability, but not so low as to burden the system with unnecessary additional water. Typically, 25-60% solids by weight is generally suitable for purposes of the present invention. For insoluble mineral suspension that are formed in situ a comparative solids percentage by weight can be achieved by factoring in the solids percent of the components that are combined to form the resulting insoluble mineral suspension. The concentration of soluble salts should be below the maximum solubility for the operating condition for a selected salt and sufficiently high enough in concentration as to not burden the system with unnecessary additional water.

[0028] Examples of a waste streams that includes precipitated suspensions of insoluble minerals which can be used as an insoluble colloidal mineral suspending according to the present invention includes slurries made from solids recovered from lime-softening of boiler water and/or cooling tower water.

[0029] While the insoluble colloidal mineral suspension used according to the present invention causes colloidal particles and very fine solid suspensions initially present in an industrial sludge to combine into larger agglomerates, it can be understood that the addition of other known coagulants and/or flocculants can also be used to aid and improved agglomeration and clumping for separation purposes

[0030] According to the present invention exemplary sludges include industrial wastewater sludges in general, refinery sludges and in particular sludges from processes such as DNF, DAF, API separators, and tank clean-out sludges.

[0031] For purposes of the present invention conventional flocculants/coagulants can also be used including mineral, natural and synthetic materials as well as those listed above.

EXAMPLES

[0032] The following non-limited Examples are provided to illustrate various features and characteristics of the present invention which are not intended to be specifically limited thereto.

Example 1

[0033] In this example DNF sludge and float were transferred from a DNF tank to a smaller tank where a 50-60% solids by weight suspension of calcium sulfate or barium sulfate in water was added at 1.5%-2.5% by volume of the DNF sludge and float. A coagulant (water soluble polymer) was added at 100 to 1000 parts per million to aid in separation. The combined mixture was heated from ambient temperature to 170 F. The heated material was then fed to a three phase centrifuge to separate clean water (centrate), oils and solids. The centrate had the characteristic of having less than 1% particulate solids and could be sent back (recovered and recycled) to the DNF or sent on to wastewater treatment. The oil could be recovered (and recycled) and the solids could be disposed of.

Example 2

[0034] In this example the same procedure in Examples 1 above was followed expect a calcium hydroxide slurry was fed into the DNF sludge and float followed by the addition of sulfuric acid to adjust pH suitable for polymer activity (pH 7-11). Alternatively the pH of the calcium hydroxide slurry can be adjusted just prior to introduction into the sludge or through the proper blending of calcium hydroxide and calcium sulfate to yield the same effective pH.

Example 3

[0035] In this example the same procedure of Example 1 and 2 above was followed except ferric chloride (an alternatively ferrous chloride) was introduced into the DNF slurry and float together with soluble alkali/alkaline hydroxide to adjust pH to form insoluble iron hydroxides.

Example 4

[0036] In this example the same procedure of Examples 1-3 above was following except soluble salts such as calcium chloride were introduced into the DNF slurry and float, followed alternatively by magnesium sulfate, sodium sulfate, or sodium carbonate, to yield the respective, insoluble calcium salts, calcium sulfate or calcium carbonate which were all proven to be effective for purposes of the present invention.

Example 5

[0037] In this example the same procedure of Example 1 above was followed except solids recovered from lime-softening of boiler water and cooling tower water was made into a slurry or alternatively recovered as a slurry, and introduced into the DNF sludge prior to separation. A 40% solution prepared from lime-softening solids was added at 1.5% by volume of the DNF sludge and float.

[0038] Although the present invention has been described with reference to particular means, materials and embodiments, from the foregoing description, one skilled in the art can easily ascertain the essential characteristics of the present invention and various changes and modifications can be made to adapt the various uses and characteristics without departing from the spirit and scope of the present invention as described above and set forth in the attached claims.