US3835996A

US3835996A - Process for the electrostatic separation of clay containing crude potassium salts

Info

Publication number: US3835996A
Application number: US00282839A
Authority: US
Inventors: A Singewald; G Fricke; D Jung
Original assignee: K+S AG
Current assignee: K+S AG
Priority date: 1972-08-22
Filing date: 1972-08-22
Publication date: 1974-09-17
Anticipated expiration: 1991-09-17

Abstract

Crude argillaceous potassium salts are separated by first subjecting the crude salt to a conditioning with 2,6dinitrophenol or a mixture of said dinitrophenol, a halogenocarboxylic acid and water and thereafter the thusconditioned salt is passed through an electrostatic separator in which a warm atmosphere is maintained, thereby producing a separation of the particles of the salt into two fractions, one containing clay and rock salt at the positive electrode and the other containing sylvite and kieserite at the negative electrode of the electrostatic separator.

Description

Singewald et al.

[ 1 Sept. 17,1974

PROCESS FOR THE ELECTROSTATIC SEPARATION OF CLAY CONTAINING CRUDE POTASSIUM SALTS Inventors: Arno Singewald, Kassel; Gunter Fricke, Neuhof; Detlef Jung, Meitingen, all of Germany Assignee: Kali and Salz AG, Kassel, Germany Filed: Aug. 22, 1972 Appl. No.: 282,839

US. Cl 209/9, 209/11, 209/127 R Int. Cl. B03b l/04 Field of Search.... 209/9, 127 R, 127 A, 127 B,

References Cited UNITED STATES PATENTS FOREIGN PATENTS OR APPLICATIONS 722,888 6/1942 Germany 209/127 R 1,078,961 4/1960 Germany 209/127 R 2,007,677 9/1971 Germany 209/9 Primary ExaminerRobert Halper Attorney, Agent, or Firm-Michael S. Striker [57] ABSTRACT Crude argillaceous potassium salts are separated by first subjecting the crude salt to a conditioning with 2,6-dinitrophenol or a mixture of said dinitrophenol, a halogenocarboxylic acid and water and thereafter the thus-conditioned salt is passed through an electrostatic separator in which a warm atmosphere is maintained, thereby producing a separation of the particles of the salt into two fractions, one containing clay and rock salt at the positive electrode and the other containing sylvite and kieserite at the negative electrode of the electrostatic separator.

9 Claims, No Drawings PROCESS FOR THE ELECTROSTATIC SEPARATION OF CLAY CONTAINING CRUDE POTASSIUM SALTS to which the salt is exposed is between 2 and 20 and most preferably between 5 and 15 percent. The salt is heated prior to the charge. The amount of 2,6- dinitrophenol should be between 50 and 500 g/t, prefhalogenocarboxylic acid and water and thereafter the 5 erably between 75 and g/te a ogenothus-conditioned salt is passed through an electrostatic carboxyhc acid Preferably is chloroacetic acid which separator in which a warm atmosphere is maintained, may be used in amounts of 50 to 500 h Ph y 0f thereby producing a separation of the particles of the 75 to 300 The water should be pfesem m amounts salt into two fractions, one containing clay and rock between 1 and 4'0O0 preferably m an amount salt at the positive electrode and the other containing 10 tween and 99 f' sylvite and kieserite at the negative electrode of the The of condmonmg by mtens've "F' may be electmstatic separaton between and 120 sec. and preferably lS between 20 and 60 sec. The separation is preferably effected at a BACKGROUND OF THE INVENTION temperature between about 25 and 65 C.

In German Pat. No. 2,007,677 an electrostatic sepah following examples will further illustrate the ration process is described for argillaceous crude potasventlon' I I sium salts wherein the salt is treated with lactic acid in The stfmmg P m examples was a y combination with a halogenmcarboxyhc acid and mite having the following chemical and screen analysis: wherein the thus conditioned mass after heating to a temperature between and 65 C is then separated 20 h i Analysis in an electrostatic separation. At the positive electrode clay separates out while the virtually clay-free crude KC| 18.61% salt is deposited at the negative electrode. The crude 1 4 salt from which the clay thus has been removed can M553 2323; then be further processed to obtain high percentage CaSO, 0.63 sylvite concentrates. :38

SUMMARY OF THE lNVENTlON 51 m It has now been found that when the conditioning is effected with dinitrophenol, specifically 2, 6- Mineral Analysis dimtrophenol, or a mixture of such dinltrophenol, a halogeno-carboxylic acid and water a reversal of the s me 7 polarity of the charge is effected in the salt. As a result Lingbeinite the argillaceous minerals will be charged negatively to- 9 y l f M gether with the rock salt and both can therefore be ob- ,i'fifi'fifi 31 3: tained directly as residual fraction. Such reversal does c sa t 5 .0 not occur with the sylvite and kieserite. These two ma- Clay terials are therefore deposited together at the positive electrode. There is thus obtained a sylvite-kieserite fraction which can either be used directly as a valuable 40 Screen Analysis K-Mg-fertilizer or can be further processed to obtain a high percentage sylvite or kieserite concentrate. There 0 8 8g is thus obtained a selective charging of the argillaceous mm materials and of the rock salt on one hand and of the 0.25 0.16 mm 8.0 7. sylvite and kieserite on the other hand. 8'}

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, ln the Tables below the following symbols have been both as to its construction and its method of operation, d; together with additional objects and advantages f ti at the positive electrode thereof, will be best understood from the following de- M middlings. scription of specific embodiments when read in confraction at the negative electrode. nection with the accompanying drawing. EXAMPLE 1 DETAILS OF EE L S E GESF SPECIFIC The tests incorporated in this Example were carried I out at a 10 percent relative humidity corresponding to Preferably the conditioning is effected by vigorous an b lute air humidity at 3947C of 57 g/m The mixing of the conditioning agent or agents with the separations were effected in a gravity (free nurse 5am ernd p iu m salt lireferablythe relative humidity tor with a throughput of about 10 t/m h:

TABLE 1 Test Conditioning K,0 contents NaCl contents Clay contents 7c No. Agent g/t 1 Fatty acid 32.2 2.2 45.4 l8.l 3.4 0.9 2 qrtbp s tis i 0 2 6. ,5 1 7 54-8. 0,7,.

2,6-dinitrophenol The tests Nos. 1 and 2 as well as Nos. 3 and 4 illustrate the prior art. They show that the argillaceous minerals have the same charge as the sylvite (Tests Nos. 1 and 2 or that they have the same charge as the rock salt and kieserite while the opposite charge is placed on the sylvite (Tests Nos. 3 and 4 which illustrate the process of the above-mentioned German patent).

Test No. 5 illustrates the process of the present invention. As appears by using 2,6-dinitrophenol as conditioning agent an equal negative charge is placed on the clay and rock salt as against the sylvite and kieserite. Accordingly there are obtained virtually clay-free sylvite-kieserite fractions at the negative electrode which can then be further processed to obtain sylvite and kieserite concentrates. The NaCl-fraction which is high in clay and comprises 78.0 percent NaCl and 4.1 percent HCl insoluble material accordingly contains only about 6 to 10 percent of the total initial sylvite. This fraction can then be discharged directly as the residual fraction and can thus be eliminated from the subsequent sylvite processing operation.

EXAMPLE 2 This Example illustrates that chloroacetic acid and water improve the effects obtained by the dinitrophenol. The sylvite then is eliminated to a higher degree in the concentrate and rock salt is eliminated at a higher amount in the residue. The combination of conditioning agents comprising 2,6-dinitrophenol, chloroacetic acid and water constitutes the optimum of the simultaneous separation of rock salt and clay on one hand and sylvite and kieserite on the other hand.

The following Table further illustrates a test with the combination of 2,6-dinitrophenol, H 0, and trichloroacetic acid. ln this test there were used the following amounts: 200 g/l dinitrophenol, 1,500 g/! water and 300 g/! trichloroacetic acid. The separations were carried out at a relative humidity of 5 percent corresponding to 55C at an absolute humidity of 5.5 g/m.

TABLE 11 NaCl Kieserite l-lCl (insoluble) Contents (71) Crude salt Concentrate Residue racttons (7r) Crude salt 1 Concentrate Residue (residue") eliminated at the positive electrode.

The process of the invention permits to obtain a common charge between the clay and the rock salt as against the charge on the sylvite and kieserite. From a crude salt containing 12.2 percent K 0 and 2.5 percent HCl insolubles there were obtained, at a single pass through the separator, a concentrate with 26.6 percent K 0 and only 0.4 percent HCl insolubles at the negative electrode. The sylvite recovery in the concentrate was 93.5 percent.

The clay fraction in the residue contained 93.7 percent of the clay which had been introduced with the crude salt and was thus eliminated. At the same time 84.5 percent of the rock salt were also eliminated in the residue.

These figures illustrate the substantial advance of the process of the invention. The separation operation can be carried out with throughputs of 5 to 30 t of crude salt per meter of width of electrode and hour. This means that the size of the electrode (width) can be reduced 30 to times as against the prior art. This thus permits huge savings in apparatus investment and cost of operation and also results in a substantial increase of the safety of the operation.

The high selectivity regarding the clay of the process of the invention is such that the clay is practically quantitatively eliminated from the salt in a single stage operation. There is thus obtained at the negative electrode a virtually clay-free crude salt which is high in K 0 contents and which can then be further processed in well known manner to obtain a higher K 0 yield and maximum concentrates with at least 60 percent. This crude salt which is free of clay and high K 0 contents has been freed of most of the rock salts. Thus in a subsequent sylvite separation operation only a comparatively low amount of salt will be deposited. This again leads to substantial savings in investments and cost of operation.

As has already been indicated the inventors have also found that water substantially increases the effects of the 2,6-dinitrophenol. The amount of water to be used dependson the relative humidity of the atmosphere to which the salt has been exposed prior to the treatment with the conditioning agents and prior to the heating to the separation temperature. Thus at a high relative humidity of the atmosphere less water need be added during the condition while the amount of water is higher at a low relative humidity. The amount of water that must be used varies between 1 and 4,000 g/t, and preferably is between 500 and 3,000 g/t.

EXAMPLE 3 The tests of this Example further illustrate the substantial advance of the process of the invention. 1. Clay and NaCl. separation according to the process of the invention are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimedas new and desired to be protected 5 6 TABLE [II by Letters Patent is set forth in the appended claims: 1. In a process for the electrostatic separation of par- Hcr Hci ticles of a crude argillaceous potassium salt which in- K20 NflCl em K2 p cludes clay, rock salt. sylvite and kieserite in which the 3% il fi {a as 5 particles of the crude salt are first subjected to treat- (7I) ment with a conditioning agent and are then charged Crude salt 2.2 520 2'5 100 100 electrostatically and passed through an electrostatic Concentrate 28.0 21.0 0.5 92.7 9.4 separator to separate the components of the crude ar- Residue gillaceous potassium salt into two fractions containing 10 different proportions of its individual components. the ll. Separation of the concentrate by conventional flotaimprovement which comprises conditioning the partition process: W clesof the crude salt intimately mixing them with a TABLE IV K o-yield K O-contents relative to relative Test 7c initial flotato crude No. concentrate residue tion mass salt l without electrostatlc pretreatment 40.0 2. l 2 86.l 86.] 2 after electrostatic pretreatment according to invention 48.6 1.38 97.8 90.6

The clay and NaCl separation according to the proconditioning agent consisting of 2-6-dinitrophenol or a cess of the invention was carried out by conditioning of mixture of 2,6-dinitrophenol and a halogenocarboxylic the argillaceous crude salt with 200 g/t 2,6- acid of the group consisting of monochloroacetic and dinitrophenol, 1,000 g/t water and 300 g/t trichloratrichloroacetic acids and water, passing the thuscetic acid at a relative humidity of 7.5 percent in 30 conditioned particles through an electrostatic separa heated air. tor in which a warm atmosphere having a relative hu- The subsequent separation by flotation of the virtumidity between 2 and percent is maintained, thereby ally clay-free concentrate of high K 0 contents was efseparating at the positive electrode a fraction predomifected with g/l guar flour, 50 g/t amine, l5 g/t oil nantly comprising clay and rock salt and, at the negaand l5 g/t of a water insoluble flotation foamer consistlive electrode, a fraction predominantly comprising syling of intermediate and higher ether-alcohols (sold vite and kieserite. under the trade-mark Flotanol by the Farbwerke Ho- 2. The process of claim 1 wherein the said dinitro- U- This is represented y test 2 O Table phenol is employed in amounts between 50 and 500 g/t. Test No. l of the same table has been added only for 3. The process of claim 1 wherein the dinitrophenol comparison purposes to show the direction flotation of i mployed in amounts between 75 and 200 g/t. a crude salt without electrostatic preceding prepara- 4. The process of claim 1 wherein the conditioning is tion. effected by vigorous mixing for a time betwee l0 and The direct flotation of the argillaceous crude salt re- 120 ds, sulted in a concentrate o 0- PerCeht 2 Which was 5. The process of claim 1 wherein the conditioning is equivalent to a K 0 yield of 86.1 percent. The flotation ff t d by vi mixi for a time betw e 20 and after treatment of a substantially clay-free concentrate 60 d as obtained by the process of the invention which was 6, Th ess of laim 1 wh in the electr t ti high in K 0 contents is shown in test No. 2. In this case separation i i d t t a tem t b tween there was obtained a flotation concentrate of 48.6 perabout 25 d 65 C Cent 2 Relative to the mass p y for the flota- 7. A process as defined in claim 1 in which the relaon step which was constituted by the concentrate Obtive humidity is maintained between 5 and 15 percent tained in T 1 the 2 Yield was 973 Pereehh 8. A process as defined in claim 1 in which the condi- Relative to the crude Sal t 2 yi was P tioning agent consists ofa mixture of 2,6-dinitrophenol, cent. the halogenocarboxylic acid and water, in which mix- The Preliminary y Separation y the ProceSS of the ture the amounts of 2,6-dinitrophenol and halogenoinvention therefore results in better K 0 concentrates b li id are h between 50 d 500 grams per and better 2 Yields in the Subsequeht y TeeOV' metric ton of the crude salt and the amount of water is ery process. between 1 and 4,000 grams per metric ton of the crude Without further analysis, the foregoing will so fully le reveal the gist of the present invention that others can 9, A process as defin d in claim 8 in which the cohdi. by applying current knowledge readily adapt it for Varitioning agent consists ofa mixture of 2,6-dinitrophenol, applications without omitting features that, from the halogenocarboxylic acid and water, in which mixthe stahdpoiht of Prior fairly constitute essential ture the amount of2,6-dinitrophenol is between 75 and characteristics of the generic or specific aspects of this 200 grams per metric ton, the amount of the halogenoinvention and, therefore, such adaptations should and carboxylic acid is between and 300 grams per metric ton, and the amount of water is between 500 and 3,000

grams per metric ton of the crude salt.

Claims

2. The process of claim 1 wherein the said dinitrophenol is employed in amounts between 50 and 500 g/t.
3. The process of claim 1 wherein the dinitrophenol is employed in amounts between 75 and 200 g/t.
4. The process of claim 1 wherein the conditioning is effected by vigorous mixing for a time betwee 10 and 120 seconds.
5. The process of claim 1 wherein the conditioning is effected by vigorous mixing for a time between 20 and 60 seconds.
6. The process of claim 1 wherein the electrostatic separation is carried out at a temperature between about 25* and 65* C.
7. A process as defined in claim 1 in which the relative humidity is maintained between 5 and 15 percent.
8. A process as defined in claim 1 in which the conditioning agent consists of a mixture of 2,6-dinitrophenol, the halogenocarboxylic acid and water, in which mixture the amounts of 2,6-dinitrophenol and halogenocarboxylic acid are each between 50 and 500 grams per metric ton of the crude salt and the amount of water is between 1 and 4,000 grams per metric ton of the crude salt.
9. A process as defined in claim 8 in which the conditioning agent consists of a mixture of 2,6-dinitrophenol, the halogenocarboxylic acid and water, in which mixture the amount of 2,6-dinitrophenol is between 75 and 200 grams per metric ton, the amount of the halogenocarboxylic acid is between 75 and 300 grams per metric ton, and the amount of water is between 500 and 3,000 grams per metric ton of the crude salt.