Method of Salts Cleaning from Higher Solubility Impurities by Virtue of Homogenization Thereof with a Solvent at a Constant Temperature

Abstract

Set forth herein is a new method of salts cleaning from higher solubilization impurities by virtue of homogenization thereof with a solvent until the obtainment of a uniform suspension and curing thereof at a constant temperature, whereby the solubility factors delta for the salts subject to separation is the highest, the salt thus cleaned being then filtered and separated from the contaminated mother solution, the latter to be recirculated to the initial point of the process for further extraction of all the remaining components of the mix.

Claims

1. A method of salts cleaning from higher solubilization impurities by virtue of homogenization thereof with a solvent and curing the resulting suspension at a constant temperature.

2. The process as per claim 1, whereby the homogenization process is to be perform until the obtainment of a paste-like suspension of the salts being subject to separation and the solvent, the salt particles having a size of less than 1 micron.

3. The process as per claim 2, whereby the solvent consumption rate in performing mix homogenization is to be defined by the quantity of the most soluble impurity subject to the solubility factor thereof.

4. The process as per claim 1, whereby in performing dry salt homogenization with the solvent, additional solvent is required with a view to obtaining upon subsequent filtration of a product containing 5% of solvent, no additional solvent being required given the use of wet salt.

5. The process as per claim 1, whereby water, acid solutions/alkali liquors as well as organic solvents, etc. may be used as the process solvent.

6. The process as per claim 2, whereby upon homogenization the resulting paste is to be agitation-cured in a mixer for ≧30 minutes at a constant temperature assuring a maximum solubility of the salt to be separated.

7. The process as per claim 1, whereby in separating multi-component mixes containing in excess of two salts, after the 1.sup.st salt separation, the next highest solubility salt is to be selected for separation, whereupon the process is to restart from the very beginning.

8. The process as per claim 1, whereby salts cleaning may be performed in a wide temperature range—from solvent freezing negative temperatures through high positive temperatures bringing the brines obtained to the boiling point.

Description

EXAMPLE 1

[0010] The study was based on the use of the saliferous brine of the Israeli de-salination plant “Palmakhim”, which is currently being waste-dumped into the sea.

[0011] Using the plant of the GHP Company, 500 liters of Palmakhim's brine yielded 490 l of fresh water, 2.9 kg of plaster-stone, (CaSO.sub.4.Math.2H.sub.2O), 7.65 liters of MgCl.sub.2 saturated brine, containing 4.000 g of MgCl.sub.2, 20 g of NaCl, 10 g of KCl (99.25% of MgCl.sub.2; 0.5% of NaCl; 0.25% of KCl) and 31 kg of a wet salts mix, containing 5% of H.sub.2O and, in terms of dry weight, MgCl.sub.2—0.4%, KCl—2.54%, NaCl—96.93%, which required the application of a salts separation process.

[0012] At the first stage, the salt was cleaned from an impurity characterized by a very high solubility, i.e. from magnesium. The salts separation process was performed at a temperature of 25° C.*. Salts solubility rates at this temperature (A Chemist's Reference Book, T3, Moscow-Leningrad, 1964) are as follows: MgCl.sub.2—585 g/l; NaCl—360 g/l; Kcl—360 g/l.

[0013] At the 1.sup.st cleaning stage, 1.5 l of distilled water was added to the wet salt, the resulting mix having been then processed in a disk grinder, the suspension thus obtained being thereupon agitation-cured for 30 minutes and filtered using a vacuum nutsch-filter. The filtration operation yielded 1.45 l of brine containing MgCl.sub.2—45 g/l; KCl—10 g/l; NaCl—310 g/l, as well as 30.45 kg of wet salt (5% H.sub.2O), cleaned from magnesium, comprising MgCl.sub.2—0.18%; KCl—2.54%; NaCl—97.28%.

[0014] The brine in the amount of 1.45 liters was recirculated to the initial stage of the process for an ultimate extraction of MgCl.sub.2 and other impurities as well as for the solvent regeneration.

[0015] At the second stage, sodium chloride was cleaned from KCl, whose content was just 2.54%. Such a low content of KCl makes it possible to separate the salts by virtue of converting potassium chloride into a liquid state and obtaining a less soluble NaCl salt in a solid state. The solubility table data showed that the highest solubility delta for the salts to be separated occurs at a temperature of 100° C. and makes for KCl—560 g/l, for NaCl—394 g/l, ΔM=166 g/l.

[0016] For purposes of separating KCl and NaCl, the magnesium-free wet salt was blended with 1.5 l of distilled water, the resulting mix being then processed in a disk-grinder at room temperature and agitation-cured in the mixer for 30 minutes at t=100° C., whereupon the pulp thus obtained was filtered.

[0017] Entrapped in the filter was sodium chloride in the amount of 28.06 kg, in terms of the composition dry weight: NaCl—99.99%; KCl—6.Math.10.sup.−3%, MgCl.sub.2—1.Math.10.sup.−4%. The filtered material in the amount of 1.43 l was cooled down to a temperature of −2.3° C. for KCl crystallization, whereupon the KCl crystals were separated from the mother solution by way of filtration. The resulting KCl crystals' weight was 734.8 g with a composition as follows: KCl—98.1%; MgCl.sub.2—0.004%; NaCl—1.9%, KCL true output being 99.5%. The mother solution in the amount of 1.4 l and the composition of was as follows: KCl—1.3 g/l; MgCl.sub.2—37.2 g/l; NaCl—50.2 g/l was recirculated to the beginning of the process for an ultimate extraction of all the salts and solvent regeneration. In all, recirculated to the initial stage of the process was 2.85 l of brine, which makes 0.6% of the initial quantity of the brine used in the process described herein.

EXAMPLE 2

[0018] For conducting tests in a different temperature range, there was prepared 1 kg of an artificial mix of the NaCl and KCl salts whose composition was equivalent to natural sylvanite: KCl—30%, NaCl—70%. This mix was cleaned at a temperature of −2.3° C. In this case, (as per the table data), NaCl solubility equals 313 g/l, whereas KCl solubility is 52 g/l. However, given a high NaCl concentration, potassium chloride is practically insoluble.

[0019] With a view to implementing salts separation, 1 kg of the salts mix was blended with 0.2 l of distilled water and homogenized using a disk-grinder at room temperature, whereupon the suspension thus obtained was placed in a refrigerator for cooling down to −2.3° C. and afterwards mixed with 2.1 l of distilled water cooled down to 0° C., the resulting pulp having been then cooled down to a temperature of −2.3° C., agitated for 30 minutes and quickly filtered. The resulting product was 290 g of KCl (in terms of dry weight) with a composition as follows: KCl—99.2%, NaCl—0.8%. Also obtained was 2.2 l of mother solution having a composition as follows: NaCl—315 g/l, KCl—1.04 g/l, which can be used for obtaining pure NaCl, with an additional extraction of KCl. In the example described above, the true output of KCl end product amounted to 95.9%.