CN107572552B - Production process for preparing potassium chloride from carnallite - Google Patents
Production process for preparing potassium chloride from carnallite Download PDFInfo
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Abstract
The invention discloses a production process for preparing potassium chloride from carnallite, which comprises the following steps: determining the critical particle size of the particles with the most average potassium chloride content, and selecting a standard screen for screening carnallite particles; screening carnallite particles into primary oversize products and primary undersize products by using a standard screen; adding water for completely dissolving magnesium chloride into the primary oversize product to obtain primary dissolved solution and primary mixed slurry; screening the primary mixed slurry into secondary oversize products and secondary undersize products by using a standard screen; carrying out reverse flotation on the primary undersize to obtain low-sodium carnallite and tail salt foam; adding water for completely dissolving magnesium chloride into the low-sodium carnallite to obtain a secondary dissolved solution and a secondary mixed slurry; carrying out solid-liquid separation on the secondary undersize product and the secondary mixed slurry to obtain a potassium crude product; and washing the obtained potassium chloride crude product to obtain a qualified potassium chloride finished product. The method has the advantages of simple operation, less investment, low energy consumption, high yield and good quality of the prepared potassium chloride finished product.
Description
Technical Field
The invention relates to the field of inorganic salt industry, in particular to a production process for preparing potassium chloride by taking carnallite as a raw material.
Background
Salt lake chemical industry generally utilizes salt pan natural evaporation to prepare carnallite, and then decomposes the carnallite to prepare potassium chloride. For example: the low sodium chloride carnallite is prepared by the reverse flotation method, the carnallite is decomposed by water, and the decomposition speed is controlled to be called as the speed-controlled crystallization method, so as to prepare the potassium chloride. Potassium chloride and picromerite are important potash fertilizers and also raw materials for producing potassium sulfate.
At present, the method for preparing potassium chloride and picromerite by using sea salt and salt lake brine mainly comprises the following steps: three process methods of a hot melting method, a flotation method and a cold decomposition crystallization method. The hot melting method has the advantages of high yield of potassium chloride, stable product quality and no influence of the quality of raw ores. Its disadvantages are high energy consumption, serious corrosion of equipment and high cost of product. The flotation method is a process for obtaining artificial sylvite after decomposing and removing magnesium from carnallite and then using octadecylamine as a collecting agent to float potassium chloride. The cold decomposition crystallization method is a new technology developed in the present year, and is characterized by that after the carnallite is undergone the process of hydrolysis, crystallization and demagging, the water is added, and washed so as to directly obtain potassium chloride crystal product.
In conclusion, the process for preparing the potassium chloride in the prior art has the problems of difficulty in obtaining raw materials meeting the process requirements, high production cost, low product quality and low environmental friendliness.
Disclosure of Invention
The method adopts the conventional carnallite screening and then carries out reverse flotation, and solves the problems that raw materials meeting the process requirements are difficult to obtain, the production cost is high, the product quality is low and the environmental friendliness is low in the prior art.
In order to solve the problems, the invention provides a production process for preparing potassium chloride from carnallite, which comprises the following steps: determination of standard sieve: classifying the carnallite particles according to particle size, and analyzing the component content of each type of carnallite particles; determining the critical particle size of the particles with the maximum potassium chloride average content; selecting a standard screen for screening carnallite particles according to the critical particle size; primary screening: screening carnallite particles into primary oversize products and primary undersize products by using a standard screen; primary magnesium removal: adding water for completely dissolving magnesium chloride into the primary oversize product to obtain primary dissolved liquid at the upper layer and primary mixed slurry at the lower layer; secondary screening: screening the primary mixed slurry into secondary oversize products and secondary undersize products by using a standard screen; reverse flotation: carrying out reverse flotation on the primary undersize to obtain low-sodium carnallite and tail salt foam; secondary magnesium removal: adding water for completely dissolving magnesium chloride into the low-sodium carnallite to obtain an upper secondary dissolved solution and a lower secondary mixed slurry; solid-liquid separation: carrying out solid-liquid separation on the secondary undersize product and the secondary mixed slurry to obtain a primary potassium chloride crude product and a secondary potassium chloride crude product; washing: and washing the primary potassium chloride crude product and the secondary potassium chloride crude product to obtain a qualified potassium chloride finished product.
Further, the critical particle size was 0.25mm, and the standard sieve was a 60-mesh sieve.
Further, the content of potassium chloride in the primary oversize product is 20-25%.
Further, the content of potassium chloride in the primary screen underflow is 7-14%.
Further, the content of potassium chloride in the secondary screen underflow is 65-70%.
Further, the content of potassium chloride in the low-sodium carnallite is 25-30%.
Further, the content of the primary potassium chloride crude product is 65-70%.
Furthermore, the content of the secondary potassium chloride crude product is 75-80%.
Further, the content of potassium chloride in the qualified potassium chloride finished product is 90-100%.
Further, the time of primary magnesium removal and secondary magnesium removal is 20 min-30 min.
Compared with the prior art, the production process for preparing the potassium chloride from the carnallite has the following advantages:
firstly, screening and reverse flotation are carried out twice, so that the yield of potassium chloride is greatly improved;
secondly, the oversize product and the dissolving solution remained in the production process are recycled for reproduction, so that the production cost is reduced, and the environmental pollution is reduced;
the production process for preparing the potassium chloride from the carnallite is mature, the operation process is simple, and the used equipment has strong preparation stability, low energy consumption, safety and reliability.
Drawings
FIG. 1 is a flow diagram of the process for producing potassium chloride from carnallite in accordance with the present invention.
Detailed Description
Referring to fig. 1, the process of the present invention for producing potassium chloride from carnallite is illustrated. The production process for preparing potassium chloride from carnallite comprises the following steps: s1, determining a standard screen: classifying the carnallite particles according to particle size, and analyzing the component content of each type of carnallite particles; determining the critical particle size of the particles with the maximum potassium chloride average content; selecting a standard screen for screening carnallite particles according to the critical particle size; s2: primary screening: screening carnallite particles into primary oversize products and primary undersize products by using a standard screen; s3: primary magnesium removal: adding water for completely dissolving magnesium chloride into the primary oversize product to obtain primary dissolved liquid at the upper layer and primary mixed slurry at the lower layer; s4: secondary screening: screening the primary mixed slurry into secondary oversize products and secondary undersize products by using a standard screen; s5: reverse flotation: carrying out reverse flotation on the primary undersize to obtain low-sodium carnallite and tail salt foam; s6: secondary magnesium removal: adding water for completely dissolving magnesium chloride into the low-sodium carnallite to obtain an upper secondary dissolved solution and a lower secondary mixed slurry; s7: solid-liquid separation: carrying out solid-liquid separation on the secondary undersize product and the secondary mixed slurry to obtain a primary potassium chloride crude product and a secondary potassium chloride crude product; s8: washing: and washing the primary potassium chloride crude product and the secondary potassium chloride crude product to obtain a qualified potassium chloride finished product. The production process for preparing potassium chloride from carnallite according to the present invention is explained in detail below.
S1, determining a standard screen: classifying the carnallite particles according to particle size, and analyzing the component content of each type of carnallite particles; determining the critical particle size of the particles with the maximum potassium chloride average content; a standard screen for screening carnallite particles is selected according to the critical particle size. The raw material carnallite particles of the invention are from the carnallite which is sun-cured, and the main components of the carnallite particles are potassium chloride, sodium chloride, magnesium chloride, calcium sulfate, insoluble impurities and the like. The carnallite grains with different grain diameters have different component contents. The particles of carnallite used in the present invention are classified and the component contents of various kinds of carnallite particles are analyzed. For example, the content of the components of the granules having a particle diameter of 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.10mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.20mm, 0.21mm, 0.22mm, 0.23mm, 0.24mm, 0.25mm, 0.26mm, 0.27mm, 0.28mm, 0.29mm, 0.30mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm, 0.36mm, 037mm, 0.38mm, 0.39mm, 0.40mm, etc. is prepared, and the content is determined by making a distribution curve of the content with respect to the particle diameter to determine the critical particle diameter of the most in the average potassium chloride content. The obtained content distribution analysis chart is shown in table 1:
TABLE 1 content of respective components of carnallite particles in a particle diameter range defined at a critical particle diameter of 0.25mm
As can be seen from the table, with 0.25mm as the critical particle size, particles having a particle size of more than 0.25mm account for 79.4% of the total weight, while particles having a particle size of less than 0.25mm account for 20.6% of the total weight. The potassium chloride and the sodium chloride have similar and very small solubility, are not easy to remove by dissolution separation, and need to be separated by reverse flotation, so that the content difference of the potassium chloride and the sodium chloride in different particle size ranges is required to be large. The magnesium chloride has high solubility and can be removed by dissolving in water. The requirement on the content difference of the particles in different ranges is not high. When the particle size is more than 0.25mm, the content of potassium chloride is 22.31 percent, the content of sodium chloride is 6.03 percent, the content of magnesium chloride is 32.55 percent, and the main components of the carnallite in the particle size range are potassium chloride and magnesium chloride; when the particle size is less than 0.25mm, the potassium chloride content is 9.95%, the sodium chloride content is 52.30%, and the magnesium chloride content is 15.70%, and the main components of the carnallite in the particle size range are sodium chloride and magnesium chloride. The content difference of the components in two particle size ranges determined by taking 0.25mm as a dividing point is large, and different processes are facilitated, so that the content of the prepared potassium chloride is increased, the starvation is realized, and the cost of the production process is reduced. After the critical grain size is determined to be 0.25mm, a screen with the corresponding mesh number of 60 meshes is selected for the subsequent screening process. The screen cloth can be selected from vibrating screen, multi-layer screen, and rotary screen, which are commonly used in the art and will not be described herein.
S2: primary screening: carnallite granules were sieved into primary oversize and primary undersize using standard sieves. According to the mesh number of the screen, carnallite particles are screened into oversize products with the particle size of more than 0.25mm and undersize products with the particle size of less than 0.25mm, and the oversize products and the undersize products are respectively collected for subsequent processes. In the invention, the content of potassium chloride in the primary oversize product is 20-25%. The content of potassium chloride in the primary screen underflow is 7 to 14 percent.
S3: primary magnesium removal: and adding water for completely dissolving the magnesium chloride into the primary oversize product to obtain an upper primary dissolved solution and a lower primary mixed slurry. According to Table 1, the potassium chloride content of the primary oversize was the highest and it was possible to remove magnesium by dissolving in water. And calculating the mass of the magnesium chloride in the oversize product according to the content of the magnesium chloride in the primary oversize product, and further calculating the water quantity required to be completely dissolved according to the solubility of the magnesium chloride. Adding calculated water into the primary oversize product to fully dissolve the primary oversize product, and because the added water theoretically allows all magnesium chloride to dissolve, most magnesium chloride and a very small amount of potassium chloride, sodium chloride and calcium sulfate can dissolve to obtain an upper primary dissolved solution, and the oversize product which is not completely dissolved forms a lower primary mixed slurry. In the invention, the time for adding water to remove magnesium is 20-30 min.
S4: secondary screening: the primary mixed slurry is screened into a secondary oversize and a secondary undersize using a standard screen. After the primary oversize product is subjected to magnesium removal, analysis shows that the solubility of sodium chloride is smaller than that of other components and is not easy to dissolve, and the particle size of particles with high sodium chloride content is not changed greatly, so that the content of magnesium chloride in other particles except particles with the component content distribution and insoluble particles is reduced, the content of potassium chloride is increased, the particle size is reduced, and most of the particle size is reduced to be less than 0.25 mm. At this point, the primary mixed slurry is again screened into a secondary oversize and a secondary undersize using a standard screen. The secondary oversize is mainly insoluble impurities and carnallite particles with higher sodium chloride content. The secondary undersize product comprises a solid phase and a primary solution, wherein the solid phase is carnallite particles with higher potassium chloride content, and the solution is a solution with higher magnesium chloride content. In the invention, the content of potassium chloride in the secondary undersize is 65-70%. The contents of the components of the secondary oversize product and the secondary undersize product are shown in table 2:
TABLE 2 contents of the ingredients of the secondary oversize and the secondary undersize
| Sample name | Content of KCl | Content of NaCl | MgCl2In an amount of | CaSO4In an amount of | Yield of potassium chloride (%) |
| Secondary oversize | 13.66％ | 59.72％ | 11.50％ | 1.07％ | |
| Crude potassium | 68.97％ | 5.32％ | 7.27％ | 0.43％ | 86.37％ |
| Once dissolving liquid | 4.00％ | 2.15％ | 25.37％ | 0.11％ |
S5: reverse flotation: and carrying out reverse flotation on the primary undersize to obtain low-sodium carnallite and tail salt foam. As can be seen from table 1, the potassium chloride content in the primary undersize was low and the sodium chloride content was high, so that the sodium chloride could be removed by reverse flotation. By adding a sodium flotation reagent, when crude ore carnallite is in a saturated flotation medium, a special reagent is added, the hydrophobicity of the surface of fine salt (NaCl) is selectively increased, but the hydrophobicity of the carnallite in the crude ore is not increased, NaCl adheres to bubbles in a flotation mechanism, floats up the surface of ore dressing slurry and is scraped out by a scraper, and the carnallite is left in the ore slurry to form tail salt foam, and the low-sodium carnallite is obtained after dehalogenation. The contents of the components of the obtained tail salt foam and the low-sodium carnallite are shown in the table 3:
TABLE 3 Tail salt foam and Low sodium carnallite content of ingredients
| Sample name | Content of KCl | Content of NaCl | MgCl2In an amount of | CaSO4In an amount of |
| Tail salt foam | 3.74％ | 81.13％ | 5.98％ | 1.60％ |
| Low sodium carnallite | 24.25％ | 2.30％ | 33.57％ | 0.67％ |
S6: secondary magnesium removal: the amount of water for dissolving the magnesium chloride is added to the low-sodium carnallite to obtain the secondary dissolved solution of the upper layer and the secondary mixed slurry of the lower layer. As can be seen from table 3, the low sodium carnallite contained a large amount of magnesium chloride, and secondary demagging was performed to increase the potassium chloride content of the low sodium carnallite. And calculating the mass of the magnesium chloride in the low-sodium carnallite according to the content of the magnesium chloride in the low-sodium carnallite, and further calculating the water quantity required to be completely dissolved according to the solubility of the magnesium chloride. The amount of water calculated is added to the low sodium carnallite to fully dissolve the low sodium carnallite, and as the theory of the amount of water added is to dissolve all the magnesium chloride, most of the magnesium chloride and a very small amount of potassium chloride, sodium chloride and calcium sulfate can be dissolved to obtain an upper secondary dissolved solution, and the upper screen which is not completely dissolved forms a lower secondary mixed slurry. The content of potassium chloride in the low-sodium carnallite is 25 to 30 percent. In the invention, the time for adding water to remove magnesium is 20-30 min. The contents of the secondary dissolved solution and the secondary mixed slurry obtained after the secondary demagging of the low-sodium carnallite were shown in table 4:
TABLE 4 contents of secondary dissolution and secondary mixed slurry obtained after secondary demagging of low-sodium carnallite
| Sample name | Content of KCl | Content of NaCl | MgCl2In an amount of | CaSO4In an amount of | Yield of potassium chloride (%) |
| Secondary solution | 3.89％ | 1.82％ | 24.85％ | 0.05％ | |
| Secondary mixed slurry | 75.75％ | 2.12％ | 4.89％ | 1.06％ | 58.62％ |
S7: solid-liquid separation: and carrying out solid-liquid separation on the secondary undersize product and the secondary mixed slurry to obtain a primary potassium chloride crude product and a secondary potassium chloride crude product. The mixed slurry is a mixture of a solid phase and a liquid phase, and a crude potassium chloride product is obtained through solid-liquid separation. The solid-liquid separation method which can be adopted comprises centrifugal separation or vacuum filtration separation, and is not described in detail herein. The content of the primary potassium chloride crude product in the invention is 65-70%. The content of the secondary potassium chloride crude product is 75-80%.
S8: washing: and washing the primary potassium chloride crude product and the secondary potassium chloride crude product to obtain a qualified potassium chloride finished product. The potassium chloride content in the primary potassium chloride crude product and the secondary potassium chloride crude product is already high, and the potassium chloride crude product becomes crude potassium at the moment, and still contains a very small amount of sodium chloride, magnesium chloride, calcium sulfate and the like. The crude product can be washed into refined potassium by adding water, namely a finished potassium chloride product and a refined potassium mother liquor. Wherein the refined potassium is divided into wet-based refined potassium and dry-based refined potassium. The potassium chloride content in the potassium chloride finished product obtained by the invention is 90-100%. And wet base refined potassium was used to calculate the yield of potassium chloride. The contents of the refined potassium mother liquor, wet-based refined potassium and dry-based refined potassium obtained by washing the primary potassium chloride crude product and the secondary potassium chloride crude product are respectively shown in tables 5 and 6:
TABLE 5 Fine Potassium mother liquor, Wet base fine Potassium and Dry base fine Potassium contents obtained by one time washing of crude Potassium chloride product
| Sample name | Content of KCl | Content of NaCl | MgCl2In an amount of | CaSO4In an amount of | Yield of potassium chloride (%) |
| Refined potassium mother liquor | 9.01％ | 7.35％ | 12.29％ | 0.27％ | |
| Refined potassium (Wet base) | 92.47％ | 1.16％ | 1.15％ | 0.19％ | 75.3％ |
| Refined potassium (Dry basis) | 97.37％ | 1.22％ | 1.21％ | 0.20％ |
TABLE 6 Fine Potassium mother liquor, Wet base fine Potassium and Dry base fine Potassium contents obtained from Secondary Potassium chloride crude product washing
| Sample name | Content of KCl | Content of NaCl | MgCl2In an amount of | CaSO4In an amount of | Yield of potassium chloride (%) |
| Refined potassium mother liquor | 8.96％ | 7.65％ | 11.98％ | 0.35％ | |
| Refined potassium (Wet base) | 91.39％ | 1.64％ | 0.81％ | 1.16％ | 55.1％ |
| Refined potassium (Dry basis) | 96.20％ | 1.73％ | 0.85％ | 1.22％ |
The process for screening and then decomposing the carnallite mine has the yield of oversize products of 75-78 percent, the yield of undersize products of 55-58 percent and the overall yield of 70-73 percent. The invention is a process method for screening the carnallite and respectively treating oversize products and undersize products after screening, wherein the oversize products do not need to be floated, and the operation is simple. The method has the advantages of less investment, low energy consumption and high yield because the amount of the screen underflow is less and only a small amount of sodium flotation reagent is needed. Compared with the process for preparing potassium chloride by cold crystallization-direct flotation and the process for preparing potassium chloride by reverse flotation-cold crystallization, the process for producing potassium chloride has the advantages that the yield is improved by about 10 percent, the production process can be utilized to improve the yield to 70 to 73 percent, the energy consumption is low, and the process operation is simple.
In the present invention, the secondary oversize product, the primary dissolution solution and the secondary dissolution solution each contain potassium chloride and other components with low contents, and they can be dried again in the air to prepare carnallite, so that the secondary oversize product, the primary dissolution solution and the secondary dissolution solution can be recovered for the production process of preparing potassium chloride from carnallite.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
The process for producing potassium chloride from carnallite according to the present invention is described in detail below with reference to several specific examples.
The present invention is implemented based on the physical properties of carnallite. Carnallite is a stable double salt with the temperature of-21 to 167.5 ℃, is a different-component double salt, and can be decomposed into another solid phase when being dissolved by adding water. The composition of pure carnallite is: KCl MgCl2·6H2In the actual production, the carnallite ore is mainly sodium chloride containing impurity salt, and the sodium chloride is removed as a main means in any potassium chloride production process. According to the method, large-particle sodium chloride and small-particle sodium chloride are separated firstly through particle size analysis of carnallite, and then the large-particle sodium chloride and the small-particle sodium chloride are separated into two procedures for treatment, so that a qualified potassium chloride product is finally obtained.
Example 1
In the experiment, 10kg of carnallite particles are used as raw materials, a 60-mesh screen is selected by taking 0.25mm as a critical particle size, and then the carnallite particles are subjected to primary screening to obtain 7.94kg of primary oversize product and 2.06kg of primary undersize product. The content of each component of carnallite was analyzed, and the analysis of the component content is shown in Table 7-1:
TABLE 7-1 weight of each component of carnallite particles in the particle size range defined by the critical particle size of 0.25mm in example 1
Primary solution and primary mixed slurry were obtained by primary demagging of 7.94kg of primary oversize. And then, carrying out secondary screening on the primary mixed slurry to obtain secondary oversize products and secondary undersize products, wherein the secondary undersize products can be separated into primary dissolved solution and primary crude potassium. After the secondary screening, the content analysis of each component is shown in Table 7-2:
TABLE 7-2 weight of each component of secondary oversize and secondary undersize
| Sample name | Weight of KCl | Weight of NaCl | MgCl2Weight of (2) | CaSO4Weight of (2) | Yield of potassium chloride (%) |
| Secondary oversize | 0.02kg | 0.07kg | 0.01kg | 0.001kg | 1.13％ |
| Primary crude potassium | 1.53kg | 0.12kg | 0.16kg | 0.009kg | 86.44％ |
| Once dissolving liquid | 0.22kg | 0.29kg | 2.41kg | 0.011kg | 12.43％ |
Next, 2.06kg of the first undersize was reverse floated to yield 0.69kg of low sodium carnallite and 1.37kg of tail salt froth. The compositional weights of the tail salt foam and low sodium carnallite are shown in tables 7-3:
TABLE 7-3 weight of ingredients for tail salt foam and low sodium carnallite
| Sample name | Weight of KCl | Weight of NaCl | MgCl2Weight of (2) | CaSO4Weight of (2) | Yield of potassium chloride (%) |
| Tail salt foam | 0.05kg | 1.06kg | 0.09kg | 0.025kg | 23.81％ |
| Low sodium carnallite | 0.16kg | 0.02kg | 0.24kg | 0.006kg | 76.19％ |
The obtained low-sodium carnallite (0.69 kg) was demagging, and water was added to the low-sodium carnallite in an amount sufficient to dissolve the magnesium chloride, to obtain a secondary mixed slurry, i.e., a mixed slurry of a secondary dissolved solution and secondary crude potassium, the weight of which is shown in Table 7-4.
TABLE 7-4 weights of secondary dissolved solution and secondary crude potassium obtained after demagging of low sodium carnallite
| Sample name | Weight of KCl | Weight of NaCl | MgCl2Weight (D) | CaSO4Weight (D) | Yield of potassium chloride (%) |
| Secondary solution | 0.066kg | 0.016kg | 0.231kg | 0.0059kg | 41.38％ |
| Secondary crude potassium | 0.094kg | 0.004kg | 0.009kg | 0.0001kg | 58.62％ |
Subsequently, the primary mixed slurry and the secondary mixed slurry were subjected to solid-liquid separation, respectively, to obtain 2.218kg of crude primary potassium chloride and 0.161kg of crude secondary potassium chloride. Adding water to the primary potassium chloride crude product and the secondary potassium chloride crude product for washing to obtain refined potassium mother liquor and wet-based refined potassium, wherein the contents of the components are shown in tables 7-5 and 7-6:
TABLE 7-5 Fine Potassium mother liquor, Wet base fine Potassium and Dry base fine Potassium contents obtained by Primary washing of crude Potassium chloride product
| Sample name | Content of KCl | Content of NaCl | MgCl2In an amount of | CaSO4In an amount of | Yield of potassium chloride (%) |
| Refined potassium mother liquor | 9.01％ | 7.35％ | 12.29％ | 0.27％ | 24.7％ |
| Refined potassium (Wet base) | 92.47％ | 1.16％ | 1.15％ | 0.19％ | 75.3％ |
| Refined potassium (Dry basis) | 97.37％ | 1.22％ | 1.21％ | 0.20％ |
TABLE 7-6 Fine Potassium mother liquor, Wet base refined Potassium and Dry base refined Potassium contents obtained by washing the crude Potassium chloride twice
| Sample name | Content of KCl | Content of NaCl | MgCl2In an amount of | CaSO4In an amount of | Yield of potassium chloride (%) |
| Refined potassium mother liquor | 8.96％ | 7.65％ | 11.98％ | 0.35％ | 44.9％ |
| Refined potassium (Wet base) | 91.39％ | 1.64％ | 0.81％ | 1.16％ | 55.1％ |
| Refined potassium (Dry basis) | 96.20％ | 1.73％ | 0.85％ | 1.22％ |
And finally, washing the primary potassium chloride crude product and the secondary potassium chloride crude product to obtain qualified potassium chloride finished products which are respectively 1.44kg and 0.13kg, wherein the overall yield of the potassium chloride is calculated to be 73.15%.
Example 2
In the experiment, 10kg of carnallite particles are used as raw materials, a 60-mesh screen is selected by taking 0.25mm as a critical particle size, and then the carnallite particles are subjected to primary screening to obtain 6.36kg of primary oversize product and 3.64kg of primary undersize product. The content of each component of carnallite was analyzed, and the analysis of the component content is shown in Table 8-1:
TABLE 8-1 weight of each component of carnallite particles in the particle size range defined by the critical particle size of 0.25mm in example 1
First solution and first mixed slurry were obtained by first demagging 6.36kg of the first oversize. And then, carrying out secondary screening on the primary mixed slurry to obtain secondary oversize products and secondary undersize products, wherein the secondary undersize products are divided into primary dissolved solution and crude potassium. After the secondary screening, the content analysis of each component was as shown in Table 8-2,
TABLE 8-2 weight of each component of secondary oversize and secondary undersize
| Sample name | Weight of KCl | Weight of NaCl | MgCl2Weight of (2) | CaSO4Weight of (2) | Yield of potassium chloride (%) |
| Secondary oversize | 0.01kg | 0.05kg | 0.01kg | 0.001kg | 0.65％ |
| Primary crude potassium | 1.29kg | 0.05kg | 0.16kg | 0.001kg | 83.77％ |
| Once dissolving liquid | 0.24kg | 0.07kg | 1.93kg | 0.006kg | 15.58％ |
Next, 3.64kg of the first undersize was reverse floated to yield 1.98kg of low sodium carnallite and 1.66kg of tail salt froth. The compositional weights of the tail salt foam and low sodium carnallite are shown in tables 8-3:
TABLE 8-3 weight of ingredients for tail salt foam and low sodium carnallite
| Sample name | Weight of KCl | Weight of NaCl | MgCl2Weight of (2) | CaSO4Weight of (2) | Yield of potassium chloride (%) |
| Tail salt foam | 0.07kg | 1.24kg | 0.12kg | 0.010kg | 12.5％ |
| Low sodium carnallite | 0.49kg | 0.05kg | 0.66kg | 0.008kg | 87.5％ |
The obtained 1.98kg of low-sodium carnallite was subjected to secondary demagging, and an amount of water for dissolving all the magnesium chloride was added to the low-sodium carnallite to obtain a secondary mixed slurry, i.e., secondary dissolved solution and secondary crude potassium in weights shown in Table 8-4.
TABLE 8-4 weights of secondary dissolved solution and secondary crude potassium obtained after secondary demagging of low sodium carnallite
| Sample name | Weight of KCl | Weight of NaCl | MgCl2Weight (D) | CaSO4Weight (D) | Yield of potassium chloride (%) |
| Secondary solution | 0.09kg | 0.04kg | 0.63kg | 0.001kg | 32.54％ |
| Secondary crude potassium | 0.40kg | 0.01kg | 0.03kg | 0.007kg | 67.46％ |
And then, respectively carrying out solid-liquid separation on the primary mixed slurry and the secondary mixed slurry to obtain 1.782kg of primary potassium chloride crude product and 0.513kg of secondary potassium chloride crude product. The crude primary potassium chloride product and the crude secondary potassium chloride product are washed by adding water to obtain refined potassium mother liquor, and the content of each component of wet refined potassium is shown in tables 8-5 and 8-6:
TABLE 8-5 Fine Potassium mother liquor, Wet base fine Potassium and Dry base fine Potassium contents obtained by one time washing of crude Potassium chloride product
| Sample name | Content of KCl | Content of NaCl | MgCl2In an amount of | CaSO4In an amount of | Yield of potassium chloride (%) |
| Refined potassium mother liquor | 9.78％ | 8.44％ | 10.25％ | 0.06％ | 24.97％ |
| Refined potassium (Wet base) | 91.90％ | 3.29％ | 1.22％ | 0.03％ | 75.03％ |
| Refined potassium (Dry basis) | 95.29％ | 3.42％ | 1.26％ | 0.03％ |
TABLE 8-6 Fine Potassium mother liquor, Wet base refined Potassium and Dry base refined Potassium contents obtained by washing the crude Potassium chloride twice
| Sample name | Content of KCl | Content of NaCl | MgCl2In an amount of | CaSO4In an amount of | Yield of potassium chloride (%) |
| Refined potassium mother liquor | 11.75％ | 14.84％ | 3.06％ | 0.11％ | 37.88％ |
| Refined potassium (Wet base) | 91.32％ | 0.64％ | 1.14％ | 1.90％ | 62.12％ |
| Refined potassium (Dry basis) | 96.12％ | 0.68％ | 1.20％ | 2.00％ |
And finally, washing the primary potassium chloride crude product and the secondary potassium chloride crude product to obtain qualified potassium chloride finished products which are respectively 1.26kg and 0.38kg, wherein the overall yield of the potassium chloride is 70.33 percent by calculation.
The foregoing description shows and describes several preferred embodiments of the present application, but as aforementioned, it is to be understood that the application is not limited to the forms disclosed herein, but is not to be construed as excluding other embodiments and is capable of use in various other combinations, modifications, and environments and is capable of changes within the scope of the inventive concept as expressed herein, commensurate with the above teachings, or the skill or knowledge of the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the application, which is to be protected by the claims appended hereto.
Claims (10)
1. A production process for preparing potassium chloride from carnallite is characterized by comprising the following steps:
determination of standard sieve: classifying the carnallite particles according to particle size, and analyzing the component content of each type of carnallite particles; making a distribution curve of the content with respect to the particle size; determining the critical particle size of the particles with the maximum potassium chloride average content; selecting said standard screen for screening said carnallite particles according to said critical particle size;
primary screening: screening the carnallite granules into primary oversize products and primary undersize products by using the standard screen;
primary magnesium removal: adding water for completely dissolving magnesium chloride into the primary oversize product to obtain primary dissolved liquid at the upper layer and primary mixed slurry at the lower layer;
secondary screening: screening the primary mixed slurry into secondary oversize products and secondary undersize products by using the standard screen;
reverse flotation: carrying out reverse flotation on the primary undersize to obtain low-sodium carnallite and tail salt foam;
secondary magnesium removal: adding water for completely dissolving magnesium chloride into the low-sodium carnallite to obtain an upper-layer secondary dissolved solution and a lower-layer secondary mixed slurry;
solid-liquid separation: carrying out solid-liquid separation on the secondary undersize product and the secondary mixed slurry to obtain a primary potassium chloride crude product and a secondary potassium chloride crude product;
washing: and washing the primary potassium chloride crude product and the secondary potassium chloride crude product to obtain a qualified potassium chloride finished product.
2. The process of claim 1 wherein the critical particle size is 0.25mm and the standard screen is a 60 mesh screen.
3. The process of claim 1, wherein the potassium chloride content of the primary oversize product is from 20% to 25%.
4. The process according to claim 1, wherein the potassium chloride content in the primary undersize is 7-14%.
5. The process for preparing potassium chloride from carnallite according to claim 1 wherein the potassium chloride content in the secondary undersize is 65% to 70%.
6. The process of claim 1 wherein the low sodium carnallite has a potassium chloride content of 25% to 30%.
7. The process for preparing potassium chloride from carnallite according to claim 1 wherein the content of the primary crude potassium chloride is 65% to 70%.
8. The process for preparing potassium chloride from carnallite according to claim 1 wherein the crude secondary potassium chloride is 75% to 80%.
9. The process of claim 1, wherein the potassium chloride content of the qualified potassium chloride product is 90-100%.
10. The process for preparing potassium chloride from carnallite according to claim 1 wherein the time for the primary and secondary demagging is 20-30 min.
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| CN108658097B (en) * | 2018-07-02 | 2020-12-15 | 青海盐湖工业股份有限公司 | Method for preparing potassium chloride by utilizing carnallite ore |
| CN109553115A (en) * | 2018-12-20 | 2019-04-02 | 青海盐湖工业股份有限公司 | A method of food-grade potassium chloride is produced using carnallite |
| CN109516477B (en) * | 2018-12-26 | 2021-10-08 | 青海盐湖工业股份有限公司 | Method and system for producing potassium chloride by using tail salt |
| CN109574043A (en) * | 2019-02-11 | 2019-04-05 | 青海盐湖工业股份有限公司 | A kind of food grade sodium chloride and its production method |
| CN111170336B (en) * | 2020-02-24 | 2022-04-22 | 青海盐湖工业股份有限公司 | Method for preparing potassium chloride from carnallite raw ore |
| CN111533138B (en) | 2020-05-06 | 2022-08-26 | 中国科学院青海盐湖研究所 | Method for preparing potassium chloride by utilizing carnallite |
| CN113751190B (en) * | 2021-09-28 | 2023-07-07 | 青海盐湖工业股份有限公司 | Method and system for preparing potassium chloride from carnallite raw ore |
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