Ground particulate spent Claus catalyst product

Abstract

Spent Claus catalyst having a high alumina content is used as an ingredient in the manufacture of Portland cements in place of all or a portion of a conventional source of alumina. The spent Claus catalyst is preferably of a small particle size and can be ground to the desired fineness before mixing with the other ingredients that are heated in a conventional kiln to produce the cement composition. Finely ground spent Claus catalyst can also be used as an additive at levels of 0.1% to 2% by weight to increase the thickening time of shallow casing cement slurries.

Claims

1. A material for use as an additive to modify the curing characteristics by increasing the thickening time of a cementitious composition that is in the form of a pumpable oilwell cement slurry for shallow casing cementing, wherein the material is spent Claus catalyst in the form of ground particles in the size range of from 6.8 to 10.4 microns.

2. A composition useful as an additive in a cementitious composition, comprising: (a) an oilwell cement slurry, and (b) the material of claim 1 wherein the material is present at approximately 2% by weight of the oilwell cement slurry.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The methods and compositions of the preferred embodiments of using the spent Claus catalyst are described in the context of the examples which follow. These examples are directed to the utilization of spent Claus catalyst as a raw material in the manufacture of Types I, II and V cement.

(2) In preparing the representative samples for this embodiment of the process and product of the invention, spent Claus catalyst having a high alumina content was blended with other conventional ingredients to manufacture a Portland cement of the type used in the construction of infrastructure and other building projects. The cured concrete product was acceptable in terms of its physical performance characteristics.

(3) In order to determine the composition of spent Claus catalyst particles, four spent Claus catalyst samples from different petroleum processing plants and processes were analyzed utilizing X-ray fluorescence spectrometry. The catalysts were presumed to be from different batches and may have been from different commercial producers. Each of the samples was ground in an agate pulverizer to a fineness of about 100 mesh and mixed thoroughly before being exposed to the X-ray beam. These samples were composed mainly of aluminum, carbon, sulfur, hydrocarbon and traces of other metals. Sample A contained higher aluminum oxide content and less carbon and hydrocarbon components when compared to other spent catalyst samples. The alumina content of the samples ranged from about 74% to 84% by weight.

(4) The composition in weight percent of four spent Claus catalysts as received are reported in Table 1.

(5) TABLE-US-00001 TABLE 1 Sample 1 Sample 2 Sample 3 Sample 4 Compound Wt % Wt % Wt % Wt % SiO.sub.2 <.01 <.01 <.01 0.01 Al.sub.2O.sub.3 83.74 74.84 75.31 74.35 Fe.sub.2O.sub.3 <.01 <.01 <.01 <.01 CaO 0.09 0.08 0.07 0.08 MgO 0.23 0.20 0.20 0.20 SO.sub.3 0.09 0.27 0.29 0.20 Na.sub.2O 0.28 0.25 0.26 0.25 K.sub.2O <.01 <.01 <.01 <.01 TiO.sub.2 <.01 <.01 <.01 <.01 P.sub.2O.sub.5 <.01 <.01 <.01 <.01 Mn.sub.2O.sub.3 0.01 0.01 0.01 0.01 SrO 0.02 0.02 0.02 0.02 Cr.sub.2O.sub.3 <.01 <.01 <.01 <.01 ZnO 0.01 0.01 0.01 0.01 L.O.I. (950 C.) 15.54 23.99 23.61 24.44 Total 100.01 99.66 99.77 99.56
The Loss on Ignition (L.O.I.) reported above was conducted at 950 C.

(6) Four different cement formulations were prepared using the four different spent Claus catalysts Samples 1-4 that are composed mainly of alumina, and were mixed with limestone, sand, clay and iron ore. A fifth (control) mix was prepared from conventional raw materials to produce five typical U.S. type V cements. The tests were conducted at an independent laboratory and are reported in Table 2. The quantities of each ingredient are in grams.

(7) TABLE-US-00002 TABLE 2 Control Mix 1 Mix 2 Mix 3 Mix 4 Limestone 1287 1362 1365 1365 1365 Clay 232 0 0 0 0 Iron Ore 26 35 35 35 35 Sand 0 113 113 113 113 Spent Claus Catalyst 0 30 30 30 30 Total 1545 1540 1543 1543 1544
The projected mineralogical composition of clinkers, as a percentage (%), is shown in Table 3.

(8) TABLE-US-00003 TABLE 3 Typical Mix Mix Mix Mix Range Control 1 2 3 4 C.sub.3S tricalcium silicate 43 to 70 60.0 60.0 61.9 60.8 60.0 C.sub.2S dicalcium silicate 11 to 31 16.6 16.3 16.0 16.1 17.0 C.sub.3A 0 to 5 3.6 4.0 4.3 4.3 4.3 tricalcium aluminate C.sub.4AF tetracalcium 10 to 19 10.9 10.9 12.1 12.2 12.2 aluminoferrite

(9) The materials utilized in the formulations of Table 2 were crushed, blended and ground in a porcelain jar mill to the fineness of 85% passing a 76 m sieve. Briquettes of about 100 grams each were prepared in a Carver hydraulic press. The specimens were pre-heated at 900 C. and fired at 1450 C. in a Blue M high-temperature furnace.

(10) After firing, the clinker briquettes having the composition of Table 3 were crushed and ground to a Blaine specific surface of 340 m.sup.2/Kg with an addition of 5% Terra Alba gypsum. The resulting cements were analyzed by XRF. The results of this analysis of the cement chemical composition, as wt %, is reported in Table 4.

(11) TABLE-US-00004 TABLE 4 Control Mix 1 Mix 2 Mix 3 Mix 4 SiO.sub.2 20.44 20.85 20.41 21.11 21.54 Al.sub.2O.sub.3 3.47 4.22 4.07 4.18 4.20 Fe.sub.2O.sub.3 3.61 4.00 3.98 4.07 4.10 CaO 64.32 63.76 64.86 63.98 63.69 MgO 2.34 1.90 1.87 1.94 1.98 SO.sub.3 2.56 2.49 2.56 2.60 2.59 Na.sub.2O 0.20 0.09 0.09 0.09 0.10 K.sub.2O 0.31 0.26 0.25 0.26 0.25 TiO.sub.2 0.21 0.13 0.13 0.14 0.14 P.sub.2 O.sub.5 0.03 0.02 0.02 0.02 0.02 Mn.sub.2O.sub.3 0.04 0.04 0.04 0.04 0.04 SrO 0.04 0.04 0.04 0.04 0.04 Cr.sub.2O.sub.3 <.01 <.01 <.01 <.01 <.01 ZnO <.01 <.01 <.01 <.01 <.01

(12) The resulting cements were tested for compressive strength in mortar cubes according to ASTM C 109, the results of which are reported in Table 5. The mortar cube strength is in psi.

(13) TABLE-US-00005 TABLE 5 Control Mix 1 Mix 2 Mix 3 Mix 4 3 days 2440 2280 2260 2380 2450 7 days 3620 3080 3140 3010 3300 28 days 4620 4670 4630 5020 5210

(14) The data in Table 5 shows some variations in the strength of cement specimens, but these variations are not significant and the specimens are considered to be of substantially the same quality. It is evident that replacement of clay with the Claus catalyst sand mix did not negatively affect the cement's performance.

(15) Another analysis was carried out to evaluate burnability of the four mixing formulations. Burnability is the term used to indicate the reactivity of the kiln feed with respect to forming clinker minerals during the burning process, and is usually measured by the free lime content of the clinker. The lower the temperature at which the targeted free lime can be obtained, the better is the burnability of the kiln feed. One procedure for characterizing the burnability of a kiln feed is to perform laboratory burns under standardized conditions and to then analyze for the resulting free lime content

(16) Results from such tests can then be compared, and the raw materials and mix compositions giving the best burnability values can be selected by comparison. Burnability can also be predicted by the chemical and mineralogical parameters of the raw mix.

(17) The burnability of the five mixes described above was evaluated according to the equations developed by F.L.Smidth as follows:
FL.sub.1400=0.31(LSFI00)+2.18(MsI.8)+0.73Q.sub.45+0.33C.sub.125+0.34A.sub.45(1)
FL.sub.1500=0.21(LSFI00)+1.59(MsI.8)+0.40Q.sub.45+0.22C.sub.125+0.08A.sub.45(2)
Where: FL.sub.1400=Virtual burnability index, or free lime content anticipated in a commercial clinker fired at 1400 C.; FL.sub.1500=same, at 1500 C.; LSF=lime saturation factor; Ms=silica ratio; Q.sub.45=% of quartz>45 m; C.sub.125=% of calcite>125 p.m; and A.sub.45=% of insoluble particles>45 m.

(18) The importance of this determination is its use in evaluating the effect of possible changes in (1) chemical composition, or (2) mineralogy and fineness, or (3) both.

(19) Both analytical and direct empirical approaches were used. For determination of the parameters included in the equations (1) and (2), the chemical parameters of the lime saturation factor and silica ratio were taken from the chemical analyses. For measurement of the particle sizes, the material was screened through Nos. 120 and 325 mesh sieves, being 125 and 45 m, respectively. The +45 m residue was treated with acetic acid to dissolve the carbonate particles. The residues were examined microscopically by a point-count technique and the particle sizes in raw mixes are reported in Table 6.

(20) TABLE-US-00006 TABLE 6 Control Mix 1 Mix 2 Mix 3 Mix 4 Residue >125 m 1.4 5.8 6.3 6.0 6.2 Calcite in residue 76.3 50.3 54.3 55.3 56.3 Calcite >125 m in 1.1 2.9 3.4 3.3 3.5 total sample >45 m residue 5.2 9.7 9.4 10.2 10.1 (acid wash) Quartz in residue 26.6 36 42.3 38.6 29 Acid-insoluble 73.4 64 57.7 61.4 71 particles >45 m in residue Quartz >45 m in 1.4 3.5 4 3.9 2.9 total sample Other acid-insoluble 3.8 6.2 5.4 6.3 7.2 particles >45 m in total sample
The results of calculations are shown in Table 7 as the virtual burnability index of the mixes

(21) TABLE-US-00007 TABLE 7 FL Control Mix 1 Mix 2 Mix 3 Mix 4 1400 2.87 5.81 6.07 6.27 5.91 1500 1.32 2.75 3.00 3.01 2.72

(22) Direct free lime determination was conducted using the following procedure. Raw meal pellets of about 13 mm in size were prepared and dried, and pre-calcined at 900 C. The pellets were further fired at 1350 C., 1400 C. and 1450 C. for 20 minutes in an electric furnace. Free CaO, or free lime content was analyzed as the principal criterion of the lime digestion which is reported in Table 8. The fired samples were also subjected to microscopic examination as will be described below.

(23) TABLE-US-00008 TABLE 8 C. Control Mix 1 Mix 2 Mix 3 Mix 4 1350 0.76 1.48 2.26 1.54 1.5 1400 0.42 0.72 0.69 0.58 0.74 1450 0.35 0.50 0.51 0.43 0.60

(24) When analyzing the data from Tables 7 and 8, it is to be noted that, due to the vastly different firing conditions in a commercial kiln and a laboratory furnace, the virtual burnability values in Table 7 are not identical to the actual free lime in Table 8. However, the values clearly demonstrate the trends in the burnability of the mixes. In the experimental burns, all mixes produced equally acceptable results. However, the data indicates that the control mix possessed better burnability characteristics due to the finer sizes of quartz and silicate particles. Generally, poor quartz grindability can lead to the necessity of finer grinding raw materials containing sand and similar ingredients to avoid problems in burning.

(25) Microscopic examination was also undertaken to detect any irregularities in the clinker formation. The purpose of this microscopic examination was to assist in the selection of the proportions of ingredients in the final cement formulations. For the purpose of this examination, the samples were identified as set forth in Table 9.

(26) TABLE-US-00009 TABLE 9 Sample ID Mix Temperature, C. C-135.sup. Control 1350 C-140.sup. Control 1400 C-145.sup. Control 1450 1-135 1 1350 1-140 1 1400 1-145 1 1450 2-135 2 1350 2-140 2 1400 2-145 2 1450 3-135 3 1350 3-140 3 1400 3-145 3 1450 4-135 4 1350 4-140 4 1400 4-145 4 1450

(27) The results of the microscopic examination indicated that spent Claus catalysts samples using clay did not lead to any abnormalities in the clinker microstructure. Certain characteristics such as non-uniform distribution and formation of belite nests can be attributed to the relatively coarse sizes of the quartz grains. Under actual production conditions, the meal fineness can be adjusted to accommodate the compositional changes.

(28) As will be understood from the above description and data, spent Claus catalyst can be successfully used to produce a high quality Portland cement for use in the construction of facilities of various types. No special processing is required prior to addition of the spend Claus catalyst to the Kiln and the processing and handling of the clinkers can continue as with the prior art formulations. The invention thus meets the objectives of disposing of significant quantities of a material that has been considered a waste by-product of the petroleum refining industry in an economical and environmental acceptable manner.

(29) A further aspect of the invention is directed to the use of spent Claus catalyst particles as an additive to modify the curing characteristics of an oilwell cement slurry for shallow casing cementing.

(30) It has been found that when spent Claus catalyst is added to shallow casing cement slurries, there is an increase in the thickening time of the shallow casing cement slurry, as measured by API10 procedures. The observed increase in thickening time occurred at additive levels of 0.1% and 2.0% of the spent catalyst.

(31) In the practice of this preferred embodiment of the invention, the spent catalyst was ground or pulverized to particles in the size range of from 6.8-10.4 microns (m) before addition to the slurry.

(32) Table 10 reports the data from the evaluation of oilwell slurry cement samples with and without the additive.

(33) TABLE-US-00010 TABLE 10 Properties Sample A Sample B Sample C Sample D Blank CI-G SACK 1.00 1.00 1.00 1.00 1.00 TWTR % VOL 100 100 100 100 100 SCC Additive 0.100 1.00 2.00 5.00 0.00 % BWOC Thickening Increase - Decrease Increase Decrease 105 Time - minutes 119

(34) Blending spent catalyst into the cement slurry of shallow casing cement jobs gives an increase in the thickening time to 119 minutes compared to 105 minutes for unmodified class G cement formulations.

(35) In order to adapt this spent catalyst for use as an additive in oilwell cement, the combined mixture of oilwell cement and spent catalyst must be easily pumpable for a sufficient time to allow proper placement of the slurry in the well. The desired consistency for the pumpable cement can be achieved by pulverizing the spent catalyst, which is in spherical form, to fine particles in the range of about 6.8-10.4 m.

(36) Although the above examples and description is comprehensive, it is intended to be illustrative and various modifications to the methods and compositions described will be apparent to those of ordinary skill in the art. The full scope of the invention is therefore to be determined with reference to the claims that follow.