Foam Prevention In The Reverse Flotation Process For Purifying Calcium Carbonate

Abstract

This invention relates to an composition, comprising A) at least one quaternary ammonium compound which is a collector for the reverse flotation of magnesium minerals from calcium carbonate B) at least one antifoam agent C) a solvent
and its use in the reverse flotation of calcium carbonate.

Claims

1-26. (canceled)

27. A process for reversely flotating magnesium silicate minerals from calcium carbonate ore, the process comprising adding a composition comprising A) at least one quaternary ammonium compound which is a collector for the reverse flotation of magnesium minerals from calcium carbonate, B) at least one antifoam agent, and C) at least one solvent to a flotation cell containing magnesium silicate minerals and calcium carbonate ore, subsequently flowing air through the flotation cell and removing the magnesium silicate minerals with the foam so generated.

28. The process according to claim 27, wherein the quaternary ammonium compound corresponds to formula (8)
[R.sup.1R.sup.2R.sup.3R.sup.4N].sup.+X.sup.(8) wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 independently from each other are hydrocarbon groups containing 1 to 30 carbon atoms, with the proviso that at least one of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 contains between 6 and 20 carbon atoms, and X is selected from the group consisting of chloride, carbonate, bicarbonate, nitrate, bromide, acetate or carboxylate.

29. The process according to claim 28, wherein the total number of carbon atoms contained in R.sup.1, R.sup.2, R.sup.3 and R.sup.4 is from 9 to 35.

30. The process according to claim 28, wherein the quaternary ammonium compound corresponds to formula (9)
[R.sup.1(CH.sub.3).sub.3N].sup.+X.sup.(9) wherein R.sup.1 is a C.sub.6-C.sub.20 hydrocarbon group.

31. The process according to claim 28, wherein the quaternary ammonium compound corresponds to formula (10)
[R.sup.1R.sup.2(CH.sub.3).sub.2N].sup.+X.sup.(10) wherein both R.sup.1 and R.sup.2 are C.sub.6-C.sub.20 hydrocarbon groups.

32. The process according to claim 28, wherein the quaternary ammonium compound corresponds to formula (11)
[R.sup.1R.sup.2(CH.sub.3).sub.2N].sup.+X.sup.(11) wherein R.sup.1 is a benzyl group and R.sup.2 is a linear C.sub.10 to C.sub.20 hydrocarbon group.

33. The process according to claim 28, wherein the quaternary ammonium compound corresponds to formula (12)
[R.sup.1R.sup.2N(CH.sub.3)((CH.sub.2CH.sub.2O).sub.nH)].sup.+X.sup.(12) wherein both R.sup.1 and R.sup.2 are independently a C.sub.6-C.sub.20 hydrocarbon group, and n is an integer from 1 to 5.

34. The process according to claim 28, wherein the quaternary ammonium compound corresponds to formula (13)
[R.sup.1R.sup.2R.sup.3(CH.sub.3)N].sup.+X.sup.(13) wherein R.sup.1, R.sup.2 and R.sup.3 independently are linear or branched C.sub.6-C.sub.20 saturated or unsaturated hydrocarbon groups.

35. The process according to claim 27, wherein X is chloride.

36. The process according to claim 27, wherein the amount of component A is from 20 to 60 wt.-%.

37. The process according to claim 27, wherein the amount of component B is from 5 to 25 wt.-%.

38. The process according to claim 27, wherein the amount of component C is from 15 to 75 wt.-%.

39. The process according to claim 27, wherein the solvent is selected from the group consisting of water, ethanol, isopropanol, 2-ethylhexanol and paraffin, or mixtures thereof.

40. The process according to claim 27, wherein the antifoam agent comprises at least one component selected from the group consisting of insoluble paraffinic and napthenic mineral oils, vegetable oils, residues from the oxo alcohol synthesis, alkylbenzenes, and crude oils from the low-temperature carbonization of brown coal or other bituminous materials.

41. The process according to claim 27, wherein the antifoam agent comprises at least one component selected from the group consisting of the compounds according to the formulae 1 to 5 ##STR00002## wherein R.sup.1 and R.sup.2 are independently from each other hydrocarbon groups having from 1 to 30, particularly from 2 to 10 carbon atoms.

42. The process according to claim 27, wherein the antifoam agent comprises at least one dimethylpolysiloxane having 2 to 2000 siloxane groups.

43. The process according to claim 27, wherein the antifoam agent comprises at least one hydrophobic silica.

44. The process according to claim 27, wherein the antifoam agent comprises at least one hydrophobic fat or wax selected from the group consisting of (1) fatty acid esters of monofunctional and polyfunctional alcohols; (2) fatty acid amides and sulfonamides; (3) paraffinic hydrocarbon waxes, ozokerite, and montan wax; (4) phosphoric acid mono-, di-, and triesters of short- and long-chain fatty alcohols; (5) short- and long-chain natural or synthetic fatty alcohols; (6) water-insoluble soaps of long-chain fatty acids; and (7) perfluorinated fatty alcohols.

45. The process according to claim 27, wherein the antifoam agent comprises at least one water-insoluble polymer selected from the group consisting of fatty acid modified alkyd resins; novolak resins; copolymers of vinyl acetate and long-chain maleic and fumaric acid diesters; methyl methacrylate-vinylpyrrolidone copolymers; poly(propylene glycols); propylene oxide adducts to glycerol, trimethylolpropane, (1,1,1-tris(hydroxymethyl)propane), pentaerythritol, triethanolamine, dipentarythritol and polyglycerol.

46. The process according to claim 27, wherein the antifoam agent comprises at least one ethoxylated alcohol corresponding to the formulae (6) and (7)
RO-(A-O).sub.nH (6)
RO-(A-O).sub.n(BO).sub.mH (7) wherein n is a number from 1 to 30 m is a number from 1 to 30 A is a C.sub.2- to C.sub.4-alkylene group B is a C.sub.2- to C.sub.4-alkylene group R is a C.sub.6- to C.sub.30-hydrocarbon group.

47. The process according to claim 46, wherein n and m independently are numbers from 2 to 10.

48. The process according to claim 36, wherein R is selected from the group consisting of alkyl and alkenyl groups.

49. The process according to claim 46, wherein formula (6) denotes a polyoxyalkylene homopolymer or a polyoxyalkylene random copolymer.

50. The process according to claim 46, wherein formula (7) denotes a polyoxyalkylene block copolymer.

51. The process according to claim 46, wherein A is a C.sub.2-alkylene group and B is a C.sub.3- or C.sub.4-alkylene group.

Description

EXAMPLES

[0106] Froth flotation experiments were conducted using a Denver laboratory flotation cell. Around 0.4 kg of ground ore was conditioned (1200 rpm) with 0.6 liters of water (solid pulp 40%). The collector was added and 1.6 l of water was added to adjust the cell flotation water content (solid pulp 15%). The pH was adjusted to 9.5 and the mixture was stirred for 2 minutes. The air intake was opened and the ore was floated during 5 minutes, obtaining the rougher concentrated and tailings. The products obtained were transferred to a tray and dried at 1055 C., following to be weighed and analyzed to determine the magnesium oxide and calcium oxide grade.

[0107] The solid pulp comprises the solid mass percentage in function of total mass percentage (solid+water) at the flotation cell.

[0108] Description of the Cylinder Foam Test: For foam stability evaluation 100 ml of the inventive emulsion were prepared and transferred to a measured cylinder of 500 ml capacity. The cylinder was shaken 10 times in a 180 movement. After the 10.sup.th movement, the chronometer was started and the foam height was measured at the start and every minute for 5 minutes. This cylinder foam test was also performed in the presence of ore simulating the pulp solid content.

[0109] Description of the Ross Miles Test (ASTM D1173/1980): In the Ross miles graduated column (1 m height) the inventive emulsion was added to reach the 0.0 ml demarcation. Another aliquot was transferred to the ampoule (200 ml) and coupled at the top of the graduated column. Then the liquid was release from the ampoule for free fall. The chronometer is started after the total liquid fell and the foam height is checked at the start and every minute for 5 minutes.

[0110] Inventive Composition Preparation:

[0111] The quaternary ammonium compound is heated to a temperature of 50 C. until all solids are molten, and is homogenized. Some homogenized quaternary ammonium compound is weighed into a beaker at 25 C. and the antifoam is added while stirring at around 100 rpm. Then, the solvent is added slowly while stirring for 30 minutes until complete homogenization is achieved. The obtained composition is clear and of yellowish colour.

[0112] Materials used:

[0113] Praepagen WB=Distearyl dimethyl ammonium chloride (Clariant S/A)

[0114] Flotigam K2C=Dimethyl Dicocoalkyl Ammonium Chloride (Clariant S/A)

[0115] Genamin T 150=Alkylamine ethoxylated (Clariant S/A)

[0116] Detalp 360=Alkyl benzenes (Deten Quimica S/A)

[0117] Isocer NL=Paraffinic oil (Isogama)

Example 1

[0118] Inventive composition 1 (table 1) was compared with a standard product in a froth flotation test. The standard product is believed to comprise a dicoco dimethyl quaternary ammonium salt solved in isopropanol. It does not contain a defoamer.

TABLE-US-00001 TABLE 1 Inventive Composition 1 for flotation test evaluation Composition content (wt.-%) Chemical compound 1 42 Praepagen WB 10 Detalp 360 5 Nonylphenol-4EO 34 Ethanol 9 Water

[0119] The flotation test results are presented at table 2, in which the inventive composition 1 presents a higher calcium recovery with a MgO content below 5.5 wt.-%, compared with the standard product results.

TABLE-US-00002 TABLE 2 Flotation performance comparison test Composition Dosage (g/ton) % MgO CaO-Recovery (%) 1 300 4.90 83.4 standard product 300 4.23 77.0 1 400 4.76 78.9 standard product 400 4.40 72.8

[0120] The foam tests were conducted comparing the composition 1 and standard product. The results (table 3) shows a lower foam in the presence of the antifoam agent.

TABLE-US-00003 TABLE 3 Foam height test comparing composition 1 and standard product. Foam Height (ml) Time (min) Cylinder Cylinder Foam Test Ross Miles (without ore) (with ore) Composition 1 Standard 1 Standard 1 Standard Instant 50.0 232.5 27.5 185.0 13.3 133.3 0.5 22.5 230.0 22.5 185.0 13.3 133.3 1 17.5 230.0 17.5 185.0 13.3 133.3 2 15.0 230.0 15.0 185.0 11.6 131.6 3 15.0 230.0 12.5 182.5 11.6 130.0 4 15.0 227.5 10.0 182.5 10.0 130.0 5 15.0 227.5 10.0 182.5 10.0 130.0

[0121] It can be concluded that composition 1 presents a lower foam formation and higher calcium recovery than the standard product.

Example 2

[0122] Inventive composition 2 was compared with the composition 2-A (both as defined in table 4) in a froth flotation test. The flotation test results are presented at table 5, in which emulsion composition 2 presents a slightly higher calcium recovery with a MgO content in both cases below 5.5 wt.-%.

TABLE-US-00004 TABLE 4 Composition 2 and 2-A for flotation test evaluation Composition Formulation (%) Chemical compound 2 42 Praepagen WB 10 Detalp 360 5 Nonylphenol-4EO 10 2-Ethylhexanol 15 Ethanol 18 Water 2-A 42 Praepagen WB 10 Detalp 360 5 Nonylphenol-4EO 10 Isocer NL 33 Ethanol

[0123] Composition 2-A avoids the use of 2-Ethylhexanol for odor reasons. 2-Ethylhexanol is replaced by the paraffin Isocer.

[0124] Table 5: Flotation Performance Comparison Test

TABLE-US-00005 TABLE 5 Flotation performance comparison test Composition Dosage (g/ton) % MgO CaO-Recovery (%) 2 200 5.75 85.0 2-A 200 5.70 86.0 2 500 5.19 85.0 2-A 500 5.33 86.0

[0125] It becomes apparent that the replacement of 2-Ethylhexanol by a paraffin does not impede the utility of the claimed invention.

Example 3

[0126] The cylinder foam tests were conducted comparing the quaternary ammonium compound in its pure form (comparative) and in the inventive form together with antifoam (compositions see Table 6). The results show a lower foam in the presence of the antifoam agent (composition 3-A, 4-A and 5-A). Both tests with and without ore presented a lower foam, in the presence of the antifoam agent (table 7 and 8).

TABLE-US-00006 TABLE 6 Foam test products composition and solution percentage Composition Solution (%) Chemical compound 3 (comp.) 0.350 Flotigam K2C 3-A 0.350 Flotigam K2C 0.115 Detalp 360 0.050 Nonylphenol-4EO 4 (comp.) 0.350 Praepagen WB 4-A 0.350 Praepagen WB 0.061 Detalp 360 0.030 Nonylphenol-4EO 0.061 2-Ethyl Hexanol 5 (comp.) 0.257 Flotigam K2C 0.092 Genamin T 150 5-A 0.257 Flotigam K2C 0.092 Genamin T 150 0.107 Detalp 360 0.045 Nonylphenol-4EO

TABLE-US-00007 TABLE 7 Cylinder foam height test in the presence of the ore Time (min) Cylinder (with ore)-Foam Height (ml) Composition 3 3-A 4 4-A 5 5-A Instant 82.5 47.5 22.5 15.0 170.0 157.5 0.5 80.0 47.5 22.5 15.0 170.0 157.5 1 77.5 47.5 22.5 15.0 170.0 157.5 2 77.5 47.5 22.5 15.0 167.5 157.5 3 77.5 47.5 22.5 15.0 167.5 155.0 4 77.5 47.5 22.5 15.0 167.5 155.0 5 75.0 47.5 22.5 15.0 167.5 155.0

TABLE-US-00008 TABLE 8 Cylinder foam height test without the ore Time (min) Cylinder (without ore)-Foam Height (ml) Composition 3 3-A 4 4-A 5 5-A Instant 67.5 45.0 32.5 20.0 135.0 120.0 0.5 67.5 45.0 30.0 20.0 135.0 120.0 1 67.5 45.0 30.0 20.0 135.0 115.0 2 67.5 45.0 30.0 20.0 135.0 110.0 3 67.5 42.5 27.5 17.5 130.0 105.0 4 67.5 40.0 27.5 15.0 127.5 102.5 5 67.5 40.0 27.5 15.0 125.0 102.5

Example 4

[0127] The Ross Miles foam tests were conducted comparing the foaming properties of quaternary ammonium compounds in absence of ore, with and without the presence of an antifoam agent (table 6). The results (table 9) shows a lower foam in the presence of the antifoam agent (composition 4-A and 5-A).

TABLE-US-00009 TABLE 9 Ross Miles foam height test without the ore Ross Milles (without ore) - Time (min) Foam Height (ml) Composition 4 4-A 5 5-A Instant 47.5 35.0 252.5 240.0 0.5 47.5 32.5 252.5 240.0 1 47.5 32.5 252.5 240.0 2 47.5 30.0 252.5 240.0 3 47.5 30.0 252.5 240.0 4 47.5 25.0 252.5 240.0 5 47.5 25.0 252.5 240.0