US3900553A - Processing tachydrite ore - Google Patents

Abstract

A solution of tachydrite ore is employed in the recovery of useful components of soluble ores. In one embodiment a tachydrite-containing solution is added to a solution containing carnallite or sylvinite ore to precipitate carnallite or sylvinite, while in another embodiment, the tachydrite-containing solution is added to a solution of halite ore to precipitate sodium chloride values.

Description

United States Patent 1191 Nylander Aug. 19, 1975 [54] PROCESSING TACHYDRITE ORE 2.699.379 1 1955 Luque 423/499 ux 2,733,257 4/1957 Duke 423/184 [761 memo Alfred Nylande." 3.498.745 3/1970 Nylander 423/184 Ave., Redwood C1ty, Callf. 94064 [22] Filed: May 14, 1973 Primary Examiner-Edward Stern [211 App]. No.: 360.000

[57] ABSTRACT 52 us. (:1. 423/184; 423/197; 423/497; A Solution of tachydrite Ore is employed in recov- 423/499 ery of useful components of soluble ores. in one em- I] In. C. o 3 0 o 3 o t 5 0 bodiment a tachydrite-containing Solution is added to [58] Field of Search H 423/499 497 184 197 a solution containing carnallite or sylvinite ore to precipitate camallite or sylvinite, while in another em [56] References Cited bodiment, the tachydrite-comaining solution is added UNITED STATES PATENTS to a solution of halite ore to precipitate sodium chloride values. 1.252.784 1/1918 Cox 423/499 x 1.863.75l 6/[932 Kipper 423/184 6 Claims, 2 Drawing Figures 2 4 2 4 V s fi 51 7 s2 54 V ss fi i 5 H l H cnmuunc mg" 140111011115 snvmn: mama ncnvnmz out out ORE 55 mus ORE -s I ,7 name 56 1111011511511 1 7 I an H 0 s2- rmcucnsa -57 2 r w 59 6| mm 1' l5 6l)\ 1s fl o mm '4 oscourosmou as mus l6 BEIIEFIGIATIOR Pommu 14,01 22\ vnogucr 51am mclmn A n 1 n LITE BLEEIJ 65 9 PRDDUOI "20 l l 21 FILTER 1 2a 0111511 raooucr w arm :53

PATEN itu i 5:: 1.1 N 05 3 LII 2 522: z 5555 a as; m5; I1 a uz fi szo 1 55 A 2223525 11 2 2 d 2;: a 3:228: 2 5:: ON: 2 3 e 5:: u GEM a 6 m: a s 5535 s T $52.: Q :5 a :0 ea: 5 E as E53: .555 E 5:: E55: E355 A e m V L o B [a m [n Q N 1 PROCESSING TACI-[YDRITE ORE DESCRIPTION OF THE INVENTION This invention relates to the mining and processing of ores and more particularly to the mining and processing of carnallite, sylvinite or halite ores in conjunction with the mining of tachydrite ore.

In the mining of ores such as those containing potash values, it is sometimes not economically feasible to dry mine the ore by sinking a shaft to the deposit. Shaft mining may be ruled out because of depth of the deposit, lack of stability of the geological formation surrounding the ore body, lack of stability of the ore body itself, or a variety of other factors. Solution mining is a possible alternative in some instances but requires a minimum ore bed height and requires that the dissolved mineral be recovered from the solution. The economic burden imposed by that recovery can be substantial and solution mining does not always constitute an economically attractive alternative. This is particularly true when the potash mineral is in a mixed bed with other soluble but economically unattractive minerals. Carnallite ore, for example, is generally regarded as an unattractice source of potassium.

The Sergipe potash deposit of Brazil and a similar deposit in the Congo of Africa are examples of potash and carnallite deposits that have not been utilized. The ore body is a complex combination of three principal constituents in semi-distinct but closely related ore zones. One zone contains sylvinite. a mixture of sylvite (KCl) and halite (NaCl), another zone contains primarily carnallite (KCI MgCl 6H O), and the third zone consists largely of tachydrite (CaCl 2MgCl l2H-,O). The make-up of the ore body, its depth, and the potential plastic flow of carnallite and tachydrite make it unlikely that shaft and drift mining of the sylvinite zone can be successful. Because of the nature of the ore body and the expense of fossil fuels or the like needed for conventional mineral recovery, solution mining has not been attempted either. Although the Sergipe deposit long has been known to exist, and although it represents a large potash reserve, the ore body remains unmined.

It is a broad object of this invention to employ a solution of tachydrite ore to recover desirable components from soluble mineral chloride ores.

It is a further object of this invention to employ a solution of tachydrite ore in the treatment of a solution of carnallite ore for the recovery of potassium values therefrom.

It is still a further object of this invention to employ a solution of tachydrite ore in the treatment of a solution of sylvinite ore for the recovery of potassium values therefrom.

It is another object of this invention to employ a solution of tachydrite ore in the treatment of a solution of a mixture of carnallite and sylvinite ores for the recovery of potassium values therefrom.

It is an additional object of this invention to employ a solution of tachydrite ore in the treatment of a solution of halite-ore to obtain sodium chloride therefrom.

In accordance with one embodiment of this invention there is provided a process which comprises:

1. forming a saturated aqueous solution of tachydrite ore;

2. forming an aqueous solution containing carnallite, sylvinite or mixtures thereof, saturated with respect to potassium chloride;

3. mixing said solutions whereby potassium chloridecontaining solids are precipitated; and

4. beneficiating said potassium chloride-containing solids to provide potassium chloride.

If carnallite is processed according to this invention the precipitated solids will contain potassium chloride and magnesium chloride; if sylvinite is processed according to this invention the precipitated solids will contain potassium chloride and sodium chloride; and if mixtures of carnallite and sylvinite are processed according to this invention the precipitated solids will contain potassium chloride, magnesium chloride and sodium chloride. As indicated below, any of these mixtures may then be beneficiated by known techniques to provide potassium chloride values.

In accordance with another embodiment of this invention, there is provided a process which comprises:

1. forming a saturated aqueous solution of tachydrite ore;

2. forming a saturated aqueous solution of halite; and

3. mixing said solutions whereby sodium chloride is precipitated.

This invention combines a solution of one unattractive ore with a solution of another ore generally regarded to be unattractive in order to obtain an economically attractive product. The solutions may be formed by solution mining the ores and the ore solutions thereafter combined to yield the desired product. Although calcium chloride-containing ore bodies such as tachy drite are not economically attractive, the use of tachydrite permits, for example, solution mining of sylvinite or carnallite to obtain potassium chloride, a valuable mineral having use, inter alia, as an agricultural nutrient. By using the tachydrite solution it is possible to precipitate carnallite or sylvinite quickly from their so lutions without the use of heat. The carnallite or sylvinite may then be processed for the recovery of potassium values by conventional techniques.

The solution mining of ores employs well known techniques and will not be described in great detail here. In one solution mining technique, two or more pipes are sunk into the desired ore body. Water or a brine, unsaturated with respect to the mineral to be dissolved, is pumped into the ore body through one or more pipes and exits from the ore body through one or more other pipes, to provide a continuous flow of liquid through the ore. In another solution mining technique, concentric pipes are employed with fluid being pumped into ore body through one pipe and removed from the ore body through the other. While solution mining is most frequently conducted as a continuous operation, it can be conducted as a batch operation in which fluid is pumped into the ore body and permitted to remain there for a period of time before being removed.

In deposits such as the Sergipe, the carnallite and tachydrite can be expected to undergo plastic deformation because of strain as some of the mineral values are removed. During solution mining of a body such as the Sergipe, the plastic deformation will tend to move the ore toward the liquid inlet thereby making the ore more readily available. The potential plastic deformation may also provide an artesian effect. Liquid may be pumped into the ore body which, upon plastic deformation, will exert sufficient pressure to cause the liquid to flow back toward the surface when the valve on the exit line is opened. This invention contemplates forming solutions underground at pressures normally encountered as well as at induced higher pressures.

The solutions employed in the practice of this inven tion are substantially saturated solutions with respect to the mineral to be recovered. While substantially complete saturation is desirable, the term saturated solution as used herein includes solutions that are at least about 80% saturated with those that are at least about 90% saturated being more desirable. The term saturated re fers to the maximum amount of the desired mineral a given solution can dissolve at the temperature of the reaction between the mineral solution and the tachydrite solution. By way of example, at 50C a saturated solution of carnallite ore will contain about 7.6 mols of KCl, 3.8 mols of NaCl and 77 mols of MgCl whereas a saturated solution of sylvinite at 50C will contain about 27 mols of KCl and 44 mols of NaCl. A 35C solution of tachydrite will contain about 26.5% CaCl about l8.5% MgCl and about 0.3% NaCl.

Generally, the temperatures at which the solutions are mixed will be those that result naturally in the process i.e., those of the mineral formation modified by the various heats of solution. It should be recognized that since the heat of solution of tachydrite is exothermic whereas the heat of solution of other minerals may be endothermic, the temperatures of the solutions coming from the ground may vary somewhat. Generally, the temperature of mixing will be within the range of from about 20C to about 60C. The mineral solution:tachydrite solution weight ratio will often be about lzl but may vary more broadly with ratios of from about l:O.5 to about 1:l.5 generally being used. The temperature for the mixing, the degree of saturation of the solutions, and the ratio of the ingredients as well as other aspects of the mixing are within the skill of the art.

The practice of this invention may more readily be understood by reference to the accompanying FIGS. 1-2 which depict typical embodiments of this invention.

FIG. 1 depicts a schematic flowsheet for the processing of carnallite ore. Water or a brine is pumped into a carnallite ore zone through line 1 and exits from the ore zone through line 2 as a substantially saturated solution of carnallite ore. A brine containing calcium chloride and magnesium chloride, or water, is introduced into a tachydrite ore zone through line 3 and exits through line 4 as a substantially saturated solution of tachydrite ore. If desired, each stream may be conducted to holding pits wherein clay or gangue may be permitted to settle out. The streams are mixed in reaction tanks 5 to form a slurry of camallite in brine. The slurry is conducted through line 6 to thickener 7 and the overflow from the thickener, a brine containing calcium chloride and magnesium chloride, is removed from the process through line 8. This stream may, if desired, be used as a source of bromine or other trace constituents which may be recovered by conventional techniques.

A portion of brine stream from line 8, if desired, may be employed as a brine to be conducted into the tachydrite ore body through line 3. inasmuch as carnallite was precipitated in reaction tanks 5, the brine stream leaving the process through line 8 is no longer saturated and, therefore, is capable of dissolving additional tachydrite ore. Since the heat of solution of calcium chloride is exothermic, the brine will tend to be heated in the tachydrite ore zone thereby aiding in the rapid solution of the tachydrite ore.

The thickened slurry from thickener 7 exits through line 9 and may, is desired, be conducted to filter 10 where it is washed with water or other solution entering through line ll. Optionally, the filtrate from filter 10 may be recycled to the thickener 7 through line 12.

The washed cake from filter 10 may be subject to beneficiation by conventional means to produce potassium chloride, and a magnesium chloride stream. In one conventional beneficiation, the solids are conducted through line 13 to decomposition tank 14 wherein they are combined with water added through line 15. Limited amounts of water are added at ambient temperatures to decompose the carnallite and provide potassium chloride solids and a magnesium chloride solution. Decomposition of carnallite with water is known in the art and provides a slurry predominately containing sylvite but which also may contain minor amounts of halite. The slurry is conducted through line 16 to thickener 17 to provide an overflow stream 18 which contains substantial amounts of magnesium chloride and sodium chloride. This stream may, if desired, be processed by conventional means to provide magnesium chloride product.

The thickened slurry from thickener I7 is conducted to filter 20 through line 19. The filter cake is washed with water introduced through line 2! and the filtrate may be recycled through line 22 to thickener l7. Following the wash, the product is removed through line 23 to drier 24 where it is dried to provide a potassium chloride product that exits at 25 and which may have a grade of 62% K 0.

FIG. 2 is a schematic flow sheet for the processing of sylvinite ore. Water or brine is pumped into the sylvinite ore zone through line 51 and exits from the ore zone through line 52 as a substantially saturated solution. A brine containing calcium chloride and magnesium chloride, or water, is introduced into the tachydrite zone through line 53 and exits from the ore zone through line 54 as a substantially saturated solution of tachydrite ore. The solutions are combined in reaction tanks 55 to form a slurry of sylvinite in brine. The slurry is conducted through line 56 to thickener 57 and the overflow from the thickener, a brine containing calcium chloride and magnesium chloride is removed from the process through line 58. This stream is a source of bromine and other trace constituents. A portion of the brine stream may, if desired, be recycled into the tachydrite ore body through line 53. Since the bleed stream is no longer saturated with regard to tachydrite, it is capable of dissolving additional ore.

The sylvinite from thickener 57 optionally may be conducted through line 59 to filter 60 where it is washed with water or brine (such as one saturated with respect to potassium chloride) introduced through line 61. The filtrate may be returned through line 62 to thickener 57. The mixture of potassium chloride and sodium chloride solids is conducted through line 63 to a beneficiation 64. The mixture of potassium chloride and sodium chloride may be beneficiated to provide potassium chloride and sodium chloride by a variety of beneficiation techniques which are well known in the art. For example, the mixture may be treated with a flo tation agent and subjected to floth flotation, the mixture may be subjected to differential crystalization, the

mixture may be selectively leached, or the like. The specifics of these techniques are well known and readily available to the art. in FIG. 2, potassium chloride product exits from the process through line 65 while halite exits through line 66.

While FIG. 1 depicts the processing of the carnallite ore and FIG. 2 depicts the processing of sylvinite ore, this invention is also applicable to solutions formed from mixtures of sylvinite and carnallite which may be encountered in mixed ore deposits such as the Sergipe deposit. Such deposit is substantially free of sulfate and readily may be processed according to this invention.

in a third embodiment of this invention, a solution saturated with respect to halite is mixed with a solution saturated with respect to tachydrite ore to provide solid sodium chloride. The slurry of sodium chloride may be processed through a thickener and thereafter filtered and washed in a manner comparable to the processing shown in FIGS. 1 and 2. It should be understood that the saturated halite solution may be formed by solution mining or may be formed as a process stream in the beneficiation of sylvinite.

The following examples are included in order to more fully illustrate the practice of this invention. These examples are included for illustrative purposes only and in no way are intended to limit the scope of this invention.

EXAMPLE 1 One part of a substantially concentrated solution of carnallite was mixed with one part of a substantially concentrated solution of tachydrite at a temperature of 50C. Solids were formed that contained magnesium chloride and potassium chloride. The solid analyzed 11.48% potassium, 8.48% magnesium, l.2% calcium and 35.58% chlorine. This mixture is suitable for processing according to the process of FIG. 1 to produce a potassium chloride product.

EXAMPLE 2 One part of a saturated solution of sylvinite was formed and mixed with one part of a saturated solution of tachydrite at 50C. The solids that formed contained potassium chloride and sodium chloride. They were analyzed and contained 18.] l% potassium, 0.68% magnesium, l.26% calcium, l9.40% sodium, and 50.6l% chlorine. This mixture is suitable for processing according to the process of FIG. 2 to provide a potassium chloride product.

EXAMPLE 3 One part of a solution saturated with carnallite ore,

one part of a solution saturated with respect to sylvinite ore and one part of a solution saturated with respect to tachydrite ore were mixed at 50C and solids were permitted to form. The solids analyzed l5.02% potassium, l.37% magnesium. 0.78% calcium, I9. I 6% sodium and 48.6% chlorine. This mixture is suitable for processing to provide potassium chloride product.

EXAMPLE 4 One part of a solution saturated with halite was mixed with one part of a saturated solution of tachydrite at 50C. The solids that formed were analyzed and contained'32.02% sodium, 53.94% chlorine, 0.55% potassium, 0.65% magnesium and l.2% calcium.

Since modification of this invention will be apparent to those skilled in the art, it is intended that this invention be limited only by the scope of the appended claims.

I claim:

1. A process which comprises:

1. forming a saturated aqueous solution of tachydrite ore;

2. forming an aqueous solution containing carnallite. sylvinite or mixtures thereof, saturated with respect to potassium chloride;

3. mixing said solutions in a mineral solution: tachydrite solution weight ratio of from about l:0.5 to about l:l.5 and at a temperature of from about 20C to about C whereby potassium chloridecontaining solids are precipitated; and

4. beneficiating said potassium chloride-containing solids to provide potassium chloride.

2. The process of claim 1 wherein said second saturated aqueous solution is a solution of carnallitc.

3. The process of claim I wherein said second saturated solution is a solution of sylvinite.

4. The process of claim I wherein said second saturation aqueous solution is a solution of a mixture of carnallite and sylvinite.

5. The process of claim 1 wherein said second aqueous solution is a solution containing carnallite and wherein said precipitated solids which contain carnallite are beneficiated by contacting them with water to form a solution containing magnesium chloride and provide a potassium chloride solids product.

6. The process of claim I wherein said second aqueous solution is a solution containing sylvinite and said precipitated potassium chloride-containing solids are subjected to froth flotation to provide a potassium chloride product.

i i 4' l l

Claims (13)

1. A PROCESS WHICH COMPRISES:

1. FRMING A STURATED AQUEOUS SOLUTION OF TACHYDRITE ORE,

2. FORMING AN AQUEOUS SOLUTION CONTAINING CARNALLITE, SYLVINITE OR MIXTURES THEREOF, SATURATED WITH RESPECT TO POTASSIUM CHLORIDE.

2. The process of claim 1 wherein said second saturated aqueous solution is a solution of carnallite.

2. forming an aqueous solution containing carnallite, sylvinite or mixtures thereof, saturated with respect to potassium chloride;

3. mixing said solutions in a mineral solution: tachydrite solution weight ratio of from about 1:0.5 to about 1:1.5 and at a temperature of from about 20*C to about 60*C whereby potassium chloride-containing solids are precipitated; and

3. The process of claim 1 wherein said second saturated solution is a solution of sylvinite.

3. MIXING SAID OLUTIONS IN A MINERAL SOLUTION: TACHYDRITE SOLUTION WEIGHT RATIO OF FROM ABOUT 1:0.5 TO ABOUT 1:1.5 AND AT A TEMPERATURE OF FROM ABOUT 20*C TO ABOUT 60*C WHEREBY POSTASSIUM CHLORIDE-CONTAINING SOLIDS ARE PREDIPUTATED AND

4. BENEFICIATING SAID POSTASSIUM CHLORIDE-CONTAINING SOLIDS TO PROVIDE POTASSIUM CHLORIDE.

4. The process of claim 1 wherein said second saturation aqueous solution is a solution of a mixture of carnallite and sylvinite.

4. beneficiating said potassium chloride-containing solids to provide potassium chloride.

5. The process of claim 1 wherein said second aqueous solution is a solution containing carnallite and wherein said precipitated solids which contain carnallite are beneficiated by contacting them with water to form a solution containing magnesium chloride and provide a potassium chloride solids product.

6. The process of claim 1 wherein said second aqueous solution is a solution containing sylvinite and said precipitated potassium chloride-containing solids are subjected to froth flotation to provide a potassium chloride product.

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