US3477566A

US3477566A - Process for the electrostatic separation of the sylvite (kci) component of a mineral

Info

Publication number: US3477566A
Application number: US600711A
Authority: US
Inventors: Hans Autenrieth; Heinrich Wirries
Original assignee: Kali Forschungs Anstalt GmbH
Current assignee: Kali Forschungs Anstalt GmbH
Priority date: 1966-03-11
Filing date: 1966-12-12
Publication date: 1969-11-11
Anticipated expiration: 1986-11-11
Also published as: DE1237514B; ES335201A1; OA02290A; FR1505274A

Description

United States Patent Int. Cl. B03b 1/04 US. Cl. 209-9 Claims ABSTRACT OF THE DISCLOSURE A process for the electrostatic separation of mineral mixtures, and. particularly to conditioned particulate crude potassium salts and the electrostatic separation thereof. In particular embodiments of thepresent invention crude particulate potassium salt mixtures are treated with inorganic mineral acids or inorganic alkaline reacting substances before, during or after the particulate material is treated with organic conditioning agents, comprising anionic compounds which form negatively charged radicals that split 01? positive ions and thereby control the electrostatic charging of the particulate material.

CROSS-REFERENCES TO RELATED APPLICATIONS 'fApplicants claim priority under 35 U.S.C. 119 for application Ser. N0. K 58,696 filed Mar. 1, 1966, in the-- Federal Republic of Germany.

BACKGROUND OF THE INVENTION It is known that minerals containing crude potassium- 3,477,566 Patented Nov. 11, 1969 DESCRIPTION OF THE INVENTION It is therefore an object of the present invention to improve efficiency and selectivity in the process of electrostatically separating particulate mineral mixtures.

Another object of the present invention is an improvement in the efficiency and selectivity of the electrostatic separation of crude potassium salts having a particulate size less than 0.1 mm.

Still another object of the present invention is an improvement in the efliciency and selectivity of the electrostatic separation of crude potassium salts containing impurities of clay.

Other objects of the present invention are improved coatings for particulate mixtures of crude potassium salts which facilitate the electrostatic separation thereof.

A particular object of the present invention is a particulate mixture of crude potassium salt having a coating comprising a mixture of an organic conditioning agent and an inorganic acid or base.

Another particular object of the present invention is a particulate mixture of crude potassium salt that is treated with an inorganic acid or base followed by a treatment with an anionic organic conditioning agent. Still another particular object of the present invention is a particulate mixture of crude potassium salt that is treated with an anionic organic conditioning agent followed by a treatment with an inorganic acid or base.

A further particular object of the present invention is a' particulate mixture of crude potassium salt that is treated with an anionic organic conditioning agent followed by treatment with gaseous hydrogen chloride or ammonia.

Upon further study of the specification and claims other objects and advantages of the present invention will become apparent.

' According to the present invention it has been found salts and manyfother mineralfniixtures 'can be separated into their components electrostatically after being preconditioned, especially by organic compounds which by forming negatively charged radicals split off one or'rnore protons or metal ions. By a suitable choice of conditioning agent, or by a combination of different conditioning agents, the electrostatic charging of the different mineral components can be controlled-so that multiple-component' systems are separated completely with high yield into individual mineral components of greater purity.

These prior art methods, conditioning agents and starting materials are fully set forth in German Patents 1,056,551, 1,061,713, 1,076,593, and 1,102,663, and the corresponding US. Patent 3,217,876, the disclosures of which are incorporated herein.

Autenrieth discloses in US. Patent 3,217,876 conditioning agents and the recycling and reconditioning of a portion of the particulate salt mixture.

The conditioning agents disclosed in the prior art patents are suitable for use in the present invention.

It is postulated that the conditioning does not depend,

like a flotation process, on a selective application of the conditioning agent to the mineral components. On the contrary, the conditioning for electrostatic separation is made without selectivity. The selective distribution of electric charges to the individual minerals is decisively favored according to the specificity of the-particular-mineral bythe application of the conditioning agent to the surfaceof the powdered mineral mixture. "The efiiciency of the prior art processes is somewhat limited by the presence of claylike components and the selectivity falls off in the smallest particle range of less than 0.1 mm.

that the specific distribution of electric charges between the minerals to be electrostatically separated is greatly improved when the powdered mixture, either before, during or after treatment with a prior art conditioning agent, is also treated with very small amounts of inorganic mineral acids, or in other cases with inorganic alkaline reacting substances, preferably NaOH, KOH, or NH OH. Even with mineral mixtures that are difficult to process, itis possible with the present invention to give them strong and highly selective charges. The unfavorable effect of claylike components, which limited the prior art processes, is to a large extent acoided thereby while at the same time the selectivity in the smallest particle range of less than 0.1 mm. diameter is considerably increased. The acids or bases which are used as additional reagents are applied advantageously as dilute or concentrated solutions in water, but are also added to the mineral mixture in their gaseous or solid state and thoroughly mixed therewith. The most suitable reagent, its most suitable concentration and the best method of adding it, depend largely on theproperties of the mineral mixture to be processed and are easily determined by those skilled in the art. 1

The electrostatic separation of the present invention is advantageously carried out with ground or pulverized particulate mineral crudes such as sylvinite and hartsalz or mixtures thereof with the separation of salts such as sylvite, kierserite, rock salt and halite.

Representative examples of the organic conditioning agents suitable for conditioning the sy'lvite containing crude ,salts or mixtures of those crude salts prior to the separation steps are among others:

3 (1) Mixtures of fatty acids C C or of parts thereof, for

instance (a) Mixtures of fatty acids C -C (b) Mixtures of fatty acids C C (c) Mixtures of fatty acids C C (d) Mixtures of fatty acids C C (e) Mixtures of fatty acids 014-022 (2) Linseed oil fatty acids; (3) Benzoic acid; (4) Phenylacetic acid; 10 (5) Salicylic acid; (6) Phthalic acid; (7) Alpha-nitroso-beta-naphthol, and salts of the above organic acids; (8) Nonyl sulfate; (9) Sodium salt of alkylsulfonic acid; (10) Sodium salt of oxystearic sulfonic acid;

be construed as merely illustrative, and not limitative of the remainder of the specification and claims in any way whatsoever.

Example 1 Crude material: Hartsalz with a K 0 content of 12.9%.

Conditioning agent: a first run fatty acid mixture having 6-12 C-atoms.

The hartsalz is ground to a fineness of less than 1.0 mm. and is first conditioned and mixed by spraying upon it 0.2 g./ kg. of a mixture of, e.g. first run fatty acids having about 612 C-atoms and is then warmed to 65 C. by a current of warm air and separated into its components by falling through a potential gradient of 4 kv./cm. in a freefall electrostatic separator. Instead of the first run fatty acids, other prior art conditioning agents are used, as suggested for example by the German and United States patents disclosed in the Background of the Invention.

TABLE I Percent K10 Percent K 0 Percent K 0 in 1st in 2nd Conditioning Agent in residue concentrate concentrate 0.2 gJkg. of first run fatty acid mixture.. 2. 5 25. 2 4 1. 0

(11) Sodium salt of benzylnaphthalenesulfonic acid; (12) Sulfonated amides of fatty acids; (13) Sodium salt of oxystearinsulfonic acid+sodium salt of alkylsulfonic acid 1:1; (14) Sodium salt of oxystearic sulfonic acid-l-sodium salt of ricinic acid 1:1; (15) Beta-nitroso-alpha-naphthol and mixtures of 1 to 15. Preferred examples of the inorganic acids used in the Further runs were then performed in which the crude salt after being conditioned with the first run fatty acid mixture was then mixed with 0.5 ml. of two normal acids per kg. of crude salt. After this second mixing the salt was warmed to 65 C. and dried by a current of warm air and then separated into its components in the same manner as disclosed above, in a free-fall separator by a potential gradient of 4 kv./ cm. The results are given in Table II.

TABLE II Percent K 0 Percent K 0 Percent K 0 in Is in 2nd Conditioning Agent in residue concentrate concentrate 0.2 g./kg. first run fatty acid- Plus 0.5 mL/kg. 2 N HCl 1. 1 40. 6 64. 0 Plus 0.5 nil/kg. 2 N H 504. 1. 1 39.3 51. 1 Plus 0.5 ml./kg. HNOa.-. 1. 3 34. 2 48. 9 Plus 0.5 mL/kg. H1304-.." 0. 0 38. 2 50. 8 Plus 0.5 ml./kg. 2 N colloidal silicic acid suspended in H 0... 1. 6 36. 0 51. 0

present invention are HCl in aqueous or gaseous form, H 80 HNO H PO and colloidal silicic acid suspended in water.

The inorganic bases preferably used in the present invention are aqueous or gaseous NH NaOH or KOH.

Combinations of mineral mixtures with a conditioning agent and an inorganic acid which particularly illustrate the new and unexpected results of the invention are hartsalz having in terms of K 0, 12.9% treated with 6 to 12 carbon atom fatty acid and HCl, H I-INO H PO 50 or colloidal silicic acid; and hartsalz having about 12-13% K 0 and 3% clay treated with 3 to 12 carbon atom fatty acid mixture, salicylic acid, phenylacetic acid, phthalic acid, or nitroso-beta-naphthol and HCl, H 80 HNO or H3PO4.

Illustrations of combinations of mineral mixtures with a conditioning agent and an inorganic base showing the new and unexpected results of the present invention include sylvinite having in terms of K 0, 18.5% and 5% clay treated with 6 to 12 carbon fatty acid and NaOH, KOH, NH OI-I or NH and sylvinite having 1516% K 0 and about 2% clay with 3 to 12 carbon fatty acid, salicylic acid, benzoic acid or phthalic acid and NaOH, KOH or NH OH.

The procedures and conditions for crushing the mineral mixture, applying the conditioning agent and carrying out the electrostatic separation are fully disclosed in U.S. Patents 3,217,876 and 3,225,924.

Before separation in the electrostatic field the preconditioned salts are preferably heated to temperatures be- 7 tween about 30 and 90 C.

Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The following preferred specific embodiments are, therefore, to

A comparison of the results of the results with and without the subsequent acid treatment shows the extraordinary improvement in the separating process. Whereas without the subsequent treatment with acid solutions the residues contained about 2.5% K 0, the residues after acid treatment contained only 0.9 to 1.6% K 0. The improvement is shown even more clearly by the concentrates. After the subsequent acid treatments the K 0 concentrations were 10-15% higher in the first separation stage than without such acid treatment, and in the second separation stage they were also 1015% higher. After such acid treatment the highest concentrates (by which is meant the end products of concentration after two or more concentrating stages) show an exceptionally high degree of purity. Whereas without acid treatment it is possible in the present case to obtain a maximum concentration of only 52% K 0 yield of 88%, after the acid treatment a maximum concentration of more than 60% K 0 with a total K 0 yield of 92% or more was obtained.

As Table III shows, the selectivity in the fine granular range that is diffcult to process is greatly improved by the acid treatment.

TABLE III Selectivity of electrostatic separation in granule size ranges up to 0.1 mm.

1 Percent K 0 in the highest concentrate.

The results listed in Table IV show that the crude salts that were separated as illustrated in Tables II and III may r. i have the process modified by subjecting the salts to the Conditioning agent: First run fatty acid mixture havacid treatment before as well as after their conditioning ing 612 C-atoms. treatment with the usual conditioning agents,.and.a1so in. The. crude salt isground to 1.0 mm. granule size and is admixture with the conditioning agents. first sprayed in with 0.2 g. of a mixture of first run fatty 5 acids having 6-12 C-atoms per kg. of crude salt, and then TABLE IV without. subsequent conditioning is warmed to 60 C. by a .current of warmairand is then separated by a potential 1 gradient of 4 kv./cm. in a free-fall separator. The sepa- Treatment with the acid before, edema;

tion of the first run fatty acids or the like. 'j p rated products are listed in Table VI.

' TABLE I Percent K20 Percent K20 Percent K20 in 1st in 2nd Conditioning agent in residue concentrate concentrate 0.2 g. first run fatty acid per lrg. crude salt 4. 7 25. 1 30. 5

Percent K 0 Percent K o in in residue 1st concentrate The high K 0 content in the residue and also the meagre Conditioning with mineral acid: enrichment of it in the concentrates show that this is not B to 22:; 20 a good processing method. After I 1.1 39.4

TABLE VII Percent K20 Percent K20 I Percent K in 1st in 2nd Conditioning Agent 7 in residue concentrate concentrate 0.2 g. first run fatty acid mixture per kg. crude salt-- Plus 0.5 ml. 2 N NaOH per kg. crude salt- 1. 9 38 49 Plus 0.5 ml. 2 N KOH per kg. crude salt..- 1. 9 38. 8 50.1 Plus 0.5 ml. 2 N NH4OH per kg. crude salt 1. 6 40. 5 52. 3 Plus 0.017 grams gaseous NH; per kg. crude salt added to the drying air 1. 5 t2. 0 54. 0

Thevalues given in Table V show that the results de- In Table VII are given the results of subsequent treatpend primarily on the amount of pure acid with which the ment with diluted alkalies, aqueous ammonia or gaseous crude salt is treated, and that the concentration of the acid ammonia added to the drying air, of the crude salt that is of only little importance. has been preconditioned with the fatty acids. In each In the separation runs listed in Table V the acid con- 35 case there was a definite improvement in the processing. centrations ranged from 4 N to gaseous, water-freeHCl. The K 0 contents of the residues are now only about /5 It is of importance only that the absolute amount of acid as high as without the use of alkalies as ancillary conis kept at an optimum value, such as can easily be deterditioning agents. The K 0 contents of the concentrates mined by one skilled in the art. are about -25% higher. TABLE v V Percent K Percent'K O 7 Percent K20 in 1st in 2nd Conditioning Agent v inresidne concentrate concentrate 0.2 g./kg. first run fatty acid- Plus 0.25 ml. 4 N HCL. 1. 0 41. 0 55. 1 Plus 0.125 ml. 8 N HCL 1. 2 42. 3 55. 0 1. 1 41. 5 54. 3

Plus 0.99 ml. 12 N nor- Example 2 Examples 3a to 3e As previously set forth in the specification, applicants *Crude material: Hartsalz with a. K 0 content of 12- have found that in somecases the treatment with inorganic 13 and 3 clay. bases is preferred to the treatment with inorganic acid. -Separation temperature: C.

TABLE VIII K20 yield Percent K20 (content of in 2nd raw material Orgamc Conditioning agent Inorganic acid concentrate equals 100%) (a) Fatty acid mixture of 0 -01; atoms, 0.2 g./kg 41.0 88 Do 56.8 94.8 Do-.- 55.1 95.4 Do-.- 54.0 95.1 Do-.- 51.1 94.9 Do 50.8 94.6 (b) salicylic acid, 0.2 2 Ike 45. 3 88. 2 Do 53. 5 95. 5 D0 54.1 93.4 (c) Phenylacetlc acid, 0.2 g./kg 46. 5 85. 6 Do 55.3 93.3 Do.-.. 45.7 95.2 1) Phthahc acid, 0.2 gJ g. 45. 1 s5. 2 D 57.3 94. 5 Do..... 55.8 94.1 (e) Nitroso- 46.0 83. 1 Do--. 53.4 95.1 Do 52.9 94.8

It is here shown that treatment with alkalics as ancillary conditioning agents results in a desired improvement. E l 4 4d As an example of this, the electrostatic processing of a clay-rich sylvinite: Crude material: Sylvrnrte with a K 0 content of 15 Raw material: Sylvinite with a K 0 content of 18.5% 16% and about 2% clay. having about 5% clay. Separation temperature: 45 C.

TABLE IX Exploited K20 of Percent K10 the crude in 2nd salt con- Organic Conditioning agent Inorganic Base concentrate taining K10 (a) Fatty eaid mixture of -01:, 0.2 g./kg 30. 79. 7 Do 2 m1.lkg.1 N NH4OH 56.8 95.7 ./kg. 1 N NHiOH 57. 1 96. 0 50. 1 94. l 52. 0 94. 7 46. 7 85. 3 56. 3 94. 7 55. 8 94. 0 46. 3 86. 3 55. 3 95. 0 55. 1 94. 8 47. 1 85. 8 58. 8 93. 2 56. 8 94. 1

The preceding examples can be repeated with similar success by substituting the generically and specifically described reactants and operating conditions of this invention for those used in the preceding examples.

We claim:

1. In a process for electrostatic separation of sylvite containing crude salt mineral, the improvement comprising: contacting saidmineral, after grinding, with a small amount of an agent selected from the group consisting of a small amount of aqueous HCl, aqueous H SO aqueous H PO aqueous NaOH, aqueous KOH, aqueous NH OH, a suspension of silicic acid in water, gaseous NH or gaseous HCl and additionally conditioning said mineral with organic conditioning agents containing an anionic organic radical and warming up said mineral in a stream of hot drying gas and subjecting said mineral to electrostatic separation of its components.

2. The electrostatic separation process of claim 1, wherein said agent is selected from the group consisting of aqueous suspensions and solutions of inorganic hydroxides.

3. The electrostatic separation process of claim 1, wherein said inorganic acids and bases are selected from the group consisting of about 200-2000 ml. of about 1.0 to 4 normal HCl, about 200-2000 ml. of about 1.0 to 4 normal H 80 about 200-2000 ml. of about 1.0 to 4 normal HNO about 200-2000 ml. of about 1.0 to 4 normal colloidal silicic acid suspended in water, about 200-2000 ml. of about 1.0 to 4 normal NaOH, about 200-2000 ml. of about 1.0 to 4 normal KO'H, about 200- 2000 ml. of about 1.0 to 4 normal NH OH, about 5-25 g. gaseous NH or about 5-25 g. HCl per ton salt mineral.

4. The process according to claim 3, wherein said inorganic agents and said anionic conditioning agents simultaneously or after mixing with said ground salt mineral are warmed up with hot gas at temperatures between about 30-90 C.

5. The electrostatic separation process of claim 3, wherein said inorganic acids and bases are selected from the group consisting of about 500-2000 ml. of about 1-2 normal HCl, about 500-2000 ml. of about 1-2 normal H 50 about 500 ml. of about 2 normal colloidal silicic acid suspended in water, about 500-2000 ml. of about 1-2 normal NaOH, about 500-2000 ml. of about 1-2 normal KOH, about 500-2000 ml. of about 1-2 normal NH OH, about 5-25 g. gaseous NH per ton salt mineral, or about 5-25 g. gaseous HCl per ton salt mineral, and said salt mineral is conditioned with a small quantity of about 200 g. of an organic anionic conditioning agent per ton salt mineral.

References Cited UNITED STATES PATENTS 2,090,418 8/ 1937 Johnson 209-127 2,188,932 2/1940 Weinig 209167 X 2,593,431 4/1952 Fraas 2099 3,008,573 11/ 1961 Gross 2099 3,049,233 8/ 1962 Marullo 209l66 3,388,794 6/ 1968 Peuschel 209--9 FOREIGN PATENTS 650,049 10/ 1962 Canada. 1,108,632 6/ 1961 Germany.

HARRY B. THORNTON, Primary Examiner R. HALPER, Assistant Examiner U.S. Cl. X.R. 209-127