Potassium chloride and sodium chloride production process

FIELD: production of inorganic compounds.

SUBSTANCE: invention is intended for use in chemical and mining industries to manufacture mineral fertilizers and food salts. Ground sylvinite ore is dissolved in recycled potassium chloride-saturated lye. Resulting solution is directed at a rate of 0.03-0.15 m/s to leaching in the first dissolution column, with its electrodes connected to one of a current source poles, and treated by low-frequency (1-5 Hz) alternating electric field at voltage 30-100 v. Solution thus enriched with potassium chloride is fed together with solid phase into the downstream second dissolution column with its electrodes connected to opposite pole of the current source. Treatment by alternating electric field in the second column is effected under the same conditions as in the first column. Two-step leaching results in potassium chloride solution and sodium chloride-enriched solid phase. Separated sodium chloride is sent to production of food salt. Potassium chloride is separated from solution via crystallization.

EFFECT: increased yield and purity of potassium and sodium chloride products and reduced power and material consumption.

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The invention relates to the processing of sylvinite and can be used for potash and other mining and chemical companies associated with the production of potassium chloride and sodium chloride.

A method of obtaining potassium chloride from sylvinite ores combined photogalleryescher method comprising flotation ore processing, classification of the obtained concentrate, dehydration selected coarse and fine fractions, leaching from the fine fraction of sodium chloride and the direction of its dissolution (A.S. USSR №1490081, 01D 3/08, 1989). This method allows to increase the yield of 1.9-2.1 times, to reduce the number of circulating flows. However, this method does not allow you to avoid high energy costs for heating and cooling of the circulating mother lye.

A method of obtaining potassium chloride, including the dissolution of the cyclone dust in a weak solution of potassium chloride after stage wet gas cleaning before saturation of a solution of 0.90-0,94 on potassium chloride, filing received undersaturated in sodium chloride solution for leaching of kristalliset potassium chloride on the centrifuges, mixing the resulting solution with a hot saturated liquor before vacuum crystallization (A.S. USSR №1490082, 01D 3/08, 1989). This method improves the extraction of useful what about the component, to improve the grain size of kristalliset, while reducing or eliminating the flow of water through the vacuum crystallization. However, this method is difficult to implement and energy intensive due to the need for heating and cooling the liquid and solid phases.

A method of obtaining potassium chloride and sodium chloride from sylvinite, including leaching of Silvinit hot solvent liquor at 105-115°containing potassium chloride and sodium chloride, processing blade, a selection of hot liquor, saturated with potassium chloride and sodium chloride, suspended solid particles in the form of a salt and clay slimes, countercurrent washing of the clay slurry with hot water to extract potassium chloride, precipitation of the salt and clay particles from a saturated solution, the removal of the salt slurry to evaporation and crystallization of potassium chloride, separating crystals of potassium chloride from the mother liquor, the processing of fatty amines heat the mother liquor and returning it to leaching (Pechkovsky CENTURIES and other Technology potash fertilizers, Moscow: Higher school, 1968, p.67-76). This method allows to obtain the potassium chloride with improved physico-chemical properties, but is associated with significant material and energy costs on heating and cooling of the liquor evaporation of sodium chloride, however, the issue of the basic units are bulky and require large production areas. In addition, the content of potassium chloride in the final product is not large enough, and significant numbers are found in the waste.

A method of obtaining potassium chloride and sodium chloride by leaching sylvinite raw materials circulating mother liquor at 100-105°and clarification of the suspension, evaporating the clarified solution with separation from him separated sodium chloride, separated from the solution by crystallization of the product containing potassium chloride, separation from the mother liquor and returning on the last stage of leaching (A.S. USSR №806605, 01D 3/04, 1981). This method is complex, energy-intensive, and the target product contains a large amount of impurities, i.e. is not sufficiently pure (purity 98%), and the degree of extraction does not exceed 91,5%.

A known way of separating potassium chloride from sylvinite, including its dissolution, the clarification received a busy liquor, crystallization of the product, the thickening of the suspension and centrifugation in the presence of the amine with the separation of the product from the filtrate and centrate, the direction of the filtrate to the processing of saturated liquor before bleaching, and centrate on stage crystallization (A.S. USSR №833507, 01D 3/08, 1981). This method has the same disadvantages as the previous one. In addition, it is not intended to obtain sodium chloride in the same process with the chloride to the lia.

A method of obtaining potassium chloride from sylvinite ores, comprising leaching the crushed Silvinit in the circulating liquor, separating nerastvorimaya ore from the liquid phase, the two-stage bleaching liquid phase, washing separated after the second stage of bleaching clay slurry, the crystallization of potassium chloride from the clarified liquor (A.S. USSR №1346578, 01D 3/08, 1987). This method has the same disadvantages as the previous one.

Closest to the claimed is a method of obtaining potassium chloride and sodium chloride from sylvinite ores, including the two-stage leaching of crushed Silvinit circulating liquor, saturated with sodium chloride and potassium chloride when heated, the selection of sodium chloride, it dewatering and leaching, crystallization, and separating potassium chloride from the mother liquor (A.S. USSR №1623954, 01D 3/06, 1991). This method allows to increase the degree of extraction of potassium chloride to 96.3%, but its cleanliness is not large enough. Although this method is less energy intensive compared with the previous methods, but, nevertheless, it requires energy costs on heating and cooling liquor, washing the clay slurry, complicated in hardware design, requires significant production areas. In addition, the resulting sodium chloride contaminated with impurities, which does not allow use is to him, therefore it is in this way is a by-product and goes to the dump.

The present invention is directed to creation of non-waste technology, providing better use of raw materials, increasing the yield and purity of target products at low energy costs, improving the efficiency and environmental friendliness of the process due to the exclusion of stages of heating and cooling liquor, washing the slurry with hot water, and reducing the manufacturing area.

The technical result consists in the reduction of material costs by eliminating from the process cycle stages of heating and cooling liquor, washing the clay slurry with hot water to extract potassium chloride, and the solution of the above tasks.

This technical result is achieved that upon receipt of potassium chloride and sodium chloride from sylvinite ores by dissolving crushed Silvinit in the circulating liquor, saturated with sodium chloride, the two-stage leaching of this solution to obtain solid and liquid phases, separation of sodium chloride from the solid phase and its subsequent dehydration, crystallization of potassium chloride from the liquid phase and separating it from the circulating liquor according to the invention the two-stage leaching is carried out under the influence of the alternating electric field is low, often the s in two columns of dissolution, serially connected in the course of the stream, provided with electrodes connected to a current source, and the electrodes of the first column is connected to one pole of the current source and the electrodes of the second column to another, and the circulating liquor is directed to the stage of dissolution of sylvinite ore. The flow in each column are served with a speed component, preferably, 0.03 to 0.15 m/s Processing the alternating electric field of low frequency in the columns of dissolution are, preferably, at a voltage of 30 to 100 V and a frequency of 1-5 Hz.

The decrease in the energy cost per unit volume of the solution is achieved by using two electric paths formed by the columns. The energy in one circuit is compensated by the energy of another, and the influence of the alternating electric field of low frequency intensifies the process of dissolution of ore and translation of potassium chloride from the ore into solution. An additional advantage of the inventive method is that the result of this used solutions are piscivorous properties in relation to contact with the equipment, therefore reducing its corrosion, increasing service life and reducing material costs.

Unexpectedly, it was found that when exposed to an alternating electric field of low frequency in the first number of the nna is incomplete (about 70%) saturation liquor potassium chloride, passing from the ore into solution. When the sodium chloride remains in the solid phase. After this, the solution with the ore served in the second column, in which processing of the alternating electric field of low frequency out of phase with respect to the first column are formed supersaturated solution of potassium chloride and sodium chloride crystals, which are separated from the insoluble residue. Then, the insoluble residue is removed from the technological cycle in the form of fine clay, which can be used in chemical, building industry and for economic purposes. The separated pure crystalline sodium chloride after washing is to receive food salts of the highest quality.

Experimentally it was found that the optimum speed of the feed streams to the column of 0.03-0.15 m/s, the voltage of the alternating electric field 30-100 In its frequency of 1-5 Hz. When changing these modes as in the smaller and higher quality and the yield of the resulting chlorides of potassium and sodium is not changed, but, on the one hand, increases the duration of the process, and on the other, increase energy consumption, although the level remains lower than in the known methods.

Apparently, the influence of the alternating electric field of low frequency causes oscillation and displacement of the molecules of salts in plants is ora, dipole moment which is different from the dipole moment of water molecules. This leads to the formation of vortex electric field, the directions of which are determined by the directions of electric fields applied to the solutions in each of the columns of dissolution from an external source. Electric field induced dipoles salts, create solutions, which are in the columns, eddy electric currents, which in 6-8 times greater than current conduction in solutions and the opposite directions of these fields are mutually suppress each other and reduce energy costs for processing per unit volume of solution. The result is the destruction of the ore particles at a constant chemical composition of salts and transition of some molecules (e.g., potassium chloride) from the ore into solution, while the other salts (e.g. sodium chloride) remain in the ore.

An example of obtaining potassium chloride and sodium chloride in accordance with the proposed method.

Sylvinite ore containing more than 70 wt.% crystalline sodium chloride and about 30 wt.% impurities, including, 26.5 wt.% potassium chloride, the rest is insoluble residue and other salts, crushed to a fraction of 1 mm Crushed ore under normal conditions (T=25°and p=0.1 MPa) is dissolved in the previously prepared circulating liquor is saturated by the Laredo sodium, containing 12,04% (148,69 g/DM³) potassium chloride, in a ratio of ore : liquor = 1:2.

The resulting solution was fed to the leaching in the first column of dissolution, which is parallel to the thread posted by the plate supply electrodes and the interelectrode space and earthing electrodes. The number of electrodes depends on the size of the column and flow rate of the solution. For example, at a flow rate of solution equal to 0.03 m/s in a column set two mains and three grounding electrode, an insulating feeding electrodes from each other. The height of the electrodes of 0.5 m, a width of 0.05 m On the supply electrodes connected to one pole of the current source serves voltage 30 C. the Direction of the electric field in the column is changed with a frequency of 1 Hz. Thus, in the first column create alternating electric field of low frequency. The processing solution in the first column should be performed within 15 sec. by creating in solution induction currents its temperature is increased, but was not more than 35°C. experiments have shown that with this arrangement of the electrodes, their number and the processing mode optimizes the output of the potassium chloride from the ore into solution. While sodium chloride is not soluble, because the solution is saturated in sodium chloride.

The resulting solution enriched in potassium chloride, together Sruthi, containing sodium chloride, served with the same speed in the second stage of leaching in the second column of dissolution, the construction of which is identical to the first column, but its supply electrodes connected to the opposite pole of the current source. Thus, two columns of dissolution and the constant current source form a closed electrical circuit. In the second column the solution is again treated with the alternating electric field of low frequency in the same mode as in the first column. By connecting the supply electrodes of the first and second columns to the opposite poles of a current source and a synchronous change their polarity in columns create the electric field of the opposite direction, i.e. the columns are out of phase with respect to each other. After processing in the second column of the resulting solution, containing 21,79% potassium chloride (271,29 g/DM³), whose temperature is 39-40°C.

The content of potassium chloride in the original liquor, ore and in the circulating liquor after dissolution was determined perchlorate method.

After processing in the second column of saturated solution of potassium chloride is separated from the solid phase by filtration. The residue after filtration, containing more than 99% sodium chloride, purified from the insoluble residue, and other salts and is directed to the production of edible sodium chloride Sol is. Saturated solution of potassium chloride after filtering fined and sent to crystallization by cooling it to room temperature. The obtained crystals contain more than 98% of potassium chloride and represent the finished product. The circulating liquor after crystallization of potassium chloride are sent to the stage of dissolution of sylvinite ore.

During the process of dissolution of the ore by leaching in two stages in the columns of dissolution without displaying liquor after the first stage, he was enriched on 36,78 g of 39,75 g, maximum, indicating a high degree of extraction of the target product.

Thus, the proposed method allows to obtain high-quality chlorides of potassium and sodium in a single process, having a purity of more than 98% and 99%, respectively. The proposed method has the following advantages:

simplicity and efficiency by eliminating energy-intensive and high-cost stage evaporation in the production of sodium chloride, exceptions stages of heating and cooling liquor and washing the clay slurry with hot water in the production of potassium chloride:

environmental safety, since it is a closed cycle with the use of recycled liquor,

- does not harm the health of the staff, because excluded harmful fumes and are not used toxi is nye and harmful chemicals.

- contributes to the reduction of production space by eliminating cumbersome and costly evaporation plants and heat exchangers and the use of compact and simple in design and operation columns dissolution;

- reduces material costs, because the solutions are piscivorous properties, resulting in no corrosion of the equipment and increases the period of its use.

1. The method of obtaining potassium chloride and sodium chloride from sylvinite ore, including the dissolution of crushed Silvinit in the circulating liquor saturated with sodium chloride, the two-stage leaching of this solution to obtain solid and liquid phases, separation of sodium chloride from the solid phase and its subsequent dehydration, crystallization of potassium chloride from the liquid phase and its separation from the circulating liquor, characterized in that the two-stage leaching is carried out under the influence of the alternating electric field of low frequency in the two columns of dissolution, connected in series along the flow, fitted with electrodes that are connected to the same current source, and the electrodes of the first column are connected to the same pole current source and the electrodes of the second column to another, and the circulating liquor after separation of the crystals of potassium chloride are sent to the stage of dissolution ismel the Chennai market.

2. The method according to claim 1, characterized in that the flow in each column are served with a speed of 0.03-0.15 m/S.

3. The method according to claim 1, characterized in that the processing of the alternating electric field of low frequency in the columns is carried out at a voltage of 30 to 100 V and a frequency of 1-5 Hz.