CN112279276B - Agricultural harmless treatment process for industrial byproduct potassium salt - Google Patents
Agricultural harmless treatment process for industrial byproduct potassium salt Download PDFInfo
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Abstract
The invention provides an agricultural harmless treatment process for industrial byproduct potassium salt, and relates to the field of industrial salt harmless treatment. An agricultural harmless treatment process for industrial byproduct potassium salt, which removes organic impurities: calcining the crushed potassium chloride solid containing impurities in a calciner, gradually heating the potassium chloride solid to 300-600 ℃ for 0.5-1.5h to obtain calcined slag: dissolving the calcined slag, adding a defluorinating agent, stirring to obtain a saturated mixed solution, filtering to obtain primary filtrate and primary filter residue, further washing and filtering the primary filter residue to obtain secondary filtrate and secondary filter residue, refluxing the secondary filtrate, dissolving the calcined slag again to obtain primary filtrate and primary filter residue, adding a heavy metal removing agent into the primary filtrate, and stirring and filtering to obtain tertiary filtrate and tertiary filter residue; the invention increases the self-supporting rate of the domestic potassium salt, has low production cost, is far lower than the price of similar products in the market, brings objective economic benefit to investors, and is beneficial to large-scale popularization.
Description
Technical Field
The invention relates to the field of industrial salt harmless treatment, in particular to an agricultural harmless treatment process for industrial byproduct potassium salt.
Background
Potassium salt refers to natural potassium-containing minerals. Including sylvite, kainite, carnallite, magnesium sulfate, potassium chloride, and the like. The potassium salts are generally soluble and have a very high purity. The potassium salt deposit comprises soluble potassium-containing minerals and brine, and is formed by evaporating, concentrating and depositing potassium-containing water. Soluble solid potassium salt deposits (e.g., sylvite, carnallite, polyhalite, etc.) and potash brine. The potash salt ore is mainly used for manufacturing potash fertilizer. The main products include potassium chloride and potassium sulfate, which are one of three fertilizers indispensable for agriculture, and only a small amount of the main products are used as chemical raw materials and applied to industry.
At present, china finds that the potassium salt resource reserves are not large, and the requirement of agriculture on potassium fertilizer is difficult to meet. Thus, potash ores are classified by the country into one of the shortfall mineral species.
On one hand, the potassium resource developed in China cannot meet the requirements of domestic industry and agriculture, and is imported in large quantities each year; on the other hand, the industrial byproduct potassium-containing waste wastes a large amount of pollution to the environment, and even leads to crop damage, yield reduction or harvest rejection for some bad merchants to be favorable for illegal use on agricultural fertilizers.
Therefore, harmless and low-cost treatment technology of industrial potassium-containing solid wastes is urgently needed to be studied.
Disclosure of Invention
The invention aims to provide an agricultural harmless treatment process for industrial byproduct potassium salt, which comprises the following steps of:
pretreatment: crushing the potassium chloride solid containing the impurities, and conveying the crushed potassium chloride solid containing the impurities into a calciner;
removing organic impurities: calcining the crushed potassium chloride solid containing impurities in a calciner, wherein the temperature of the potassium chloride solid is gradually increased to 300-600 ℃, the calcining time is 0.5-1.5h, the calcining slag is obtained, the organic matters in the potassium chloride solid are gradually increased, decomposed and volatilized, and the calcination is carried out again in a high-temperature environment, the calcining temperature is 1000-1200 ℃, and the calcining time is 2S-3S;
removing inorganic impurities: dissolving the calcined slag, adding a defluorinating agent, stirring to obtain a saturated mixed solution, filtering to obtain primary filtrate and primary filter residue, further washing and filtering the primary filter residue to obtain secondary filtrate and secondary filter residue, refluxing the secondary filtrate to dissolve the calcined slag again to obtain primary filtrate and primary filter residue, adding the heavy metal removing agent into the primary filtrate, and stirring and filtering to obtain tertiary filtrate and tertiary filter residue;
crystallization separation: crystallizing the tertiary filtrate, then obtaining potassium chloride solid and mother liquor through centrifugal separation, and sending the mother liquor back to the system for recrystallization separation.
Compared with the prior art, the embodiment of the invention has at least the following advantages or beneficial effects:
the embodiment of the application provides an agricultural harmless treatment process for industrial byproduct potassium salt, which comprises the following steps: pretreatment: crushing the potassium chloride solid containing the impurities, and conveying the crushed potassium chloride solid containing the impurities into a calciner; removing organic impurities: calcining the crushed potassium chloride solid containing impurities in a calciner, wherein the temperature of the potassium chloride solid is gradually increased to 300-600 ℃, the calcining time is 0.5-1.5h, the calcining slag is obtained, the organic matters in the potassium chloride solid are gradually increased, decomposed and volatilized, and the calcination is carried out again in a high-temperature environment, the calcining temperature is 1000-1200 ℃, and the calcining time is 2S-3S; removing inorganic impurities: dissolving the calcined slag, adding a defluorinating agent, stirring to obtain a saturated mixed solution, filtering to obtain primary filtrate and primary filter residue, further washing and filtering the primary filter residue to obtain secondary filtrate and secondary filter residue, refluxing the secondary filtrate to dissolve the calcined slag again to obtain primary filtrate and primary filter residue, adding the heavy metal removing agent into the primary filtrate, and stirring and filtering to obtain tertiary filtrate and tertiary filter residue; crystallization separation: crystallizing the tertiary filtrate, then obtaining potassium chloride solid and mother liquor through centrifugal separation, and sending the mother liquor back to the system for recrystallization separation. Calcining the crushed potassium chloride solid containing impurities in a calciner, preparing calcined slag into a solution in a dissolving tank, adding a defluorinating agent, stirring to obtain a saturated mixed solution, filtering to obtain primary filtrate and primary filter residue, further washing and filtering the primary filter residue to obtain secondary filtrate and secondary filter residue, and returning the secondary filtrate to the primary dissolving tank; adding a heavy metal removing agent into the first-stage filtrate, stirring and filtering to obtain third-stage filtrate and third-stage filter residue; crystallization separation: and (3) evaporating and crystallizing the tertiary filtrate, and then obtaining potassium chloride solid and mother liquor through centrifugal separation, and returning the mother liquor to an evaporating crystallizer for continuous evaporation.
The method has the advantages that the effect of calcining the impurity-containing potassium chloride solid can be effectively improved by crushing the impurity-containing potassium chloride solid into particles, the potassium chloride solid particles can be fully heated and calcined and organic matters in the impurities can be separated, the calcined slag after the internal organic matters are burnt or carbonized is calcined under the high-temperature aerobic condition of the materials, the calcined slag is added with different treatment medicaments to separate and filter inorganic matters in the calcined slag, the cost is low, the inorganic matters are separated by adding different treatment medicaments, the separation effect on the inorganic matters is comprehensive and efficient, the solute component in the filtrate after the inorganic matters is separated is basically potassium chloride, and the high-purity potassium chloride crystal is prepared by a crystallization treatment mode.
The invention increases the self-supporting rate of the domestic potassium salt, has low production cost, is far lower than the price of similar products in the market, brings objective economic benefit to investors, and is beneficial to large-scale popularization.
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In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of an agricultural harmless treatment process of potassium salt in the embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other. The present invention will be described in detail with reference to specific examples.
An agricultural harmless treatment process for industrial byproduct potassium salt, which comprises the following steps:
pretreatment: crushing the potassium chloride solid containing the impurities, and conveying the crushed potassium chloride solid containing the impurities into a calciner;
removing organic impurities: calcining the crushed potassium chloride solid containing impurities in a calciner, wherein the temperature of the potassium chloride solid is gradually increased to 300-600 ℃, the calcining time is 0.5-1.5h, the calcining slag is obtained, the organic matters in the potassium chloride solid are gradually increased, decomposed and volatilized, and the calcination is carried out again in a high-temperature environment, the calcining temperature is 1000-1200 ℃, and the calcining time is 2S-3S;
removing inorganic impurities: dissolving the calcined slag, adding a defluorinating agent, stirring to obtain a saturated mixed solution, filtering to obtain primary filtrate and primary filter residue, further washing and filtering the primary filter residue to obtain secondary filtrate and secondary filter residue, refluxing the secondary filtrate to dissolve the calcined slag again to obtain primary filtrate and primary filter residue, adding the heavy metal removing agent into the primary filtrate, and stirring and filtering to obtain tertiary filtrate and tertiary filter residue;
crystallization separation: crystallizing the tertiary filtrate, then obtaining potassium chloride solid and mother liquor through centrifugal separation, and sending the mother liquor back to the system for recrystallization separation.
In the embodiment, the effect of calcination can be effectively improved by crushing the potassium chloride solid containing impurities into particles and calcining the particles, so that the potassium chloride solid particles can be fully heated and calcined to separate organic matters in the impurities, the calcined slag after the organic matters in the material are burnt or carbonized is calcined under the high-temperature aerobic condition, the calcined slag is added with different treatment medicaments to separate and filter inorganic matters in the calcined slag, the inorganic matters are separated by adding different treatment medicaments, the cost is low, the separation effect on the inorganic matters is relatively comprehensive and efficient, the solute component in the filtrate after the inorganic matters are separated is basically potassium chloride, and high-purity potassium chloride crystals are prepared by a crystallization treatment mode. The invention increases the self-supporting rate of the domestic potassium salt, has low production cost, is far lower than the price of similar products in the market, brings objective economic benefit to investors, and is beneficial to large-scale popularization.
In some embodiments of the invention, the fluorine scavenger is one of calcium chloride, magnesium chloride or calcium magnesium salt.
The defluorinating agent adopted in the embodiment is calcium chloride, a calcium chloride solvent reacts with fluoride ions in the primary filter residue to generate calcium fluoride, the calcium fluoride is an inorganic compound, the chemical formula is CaF2, and the calcium fluoride is colorless crystal or white powder, is indissolvable in water, and is used for removing the fluoride ions in the primary filter residue and generating precipitate for effective filtering treatment.
The defluorinating agent adopted in the embodiment is magnesium chloride, the magnesium chloride solvent reacts with fluoride ions in the primary filter residue to generate magnesium fluoride, the magnesium fluoride is also called magnesium difluoride, the molecular formula is MgF2, and the defluorinating agent is colorless tetragonal crystal or powder, is odorless, is indissolvable in water, removes the fluoride ions in the primary filter residue through the defluorinating agent, generates sediment and carries out effective filtration treatment.
In some embodiments of the present invention, the heavy metal removing agent is an anionic salt solution containing a heavy metal salt which is hardly soluble in water.
In this embodiment, the heavy metal removing agent is a solution containing anions which can generate heavy metal salts which are difficult to be dissolved in water, and the solution containing the anions is added into a mixed solution of the primary filtrate and the secondary filtrate, so that the anions react with the heavy metal ions in the mixed solution to generate heavy metal precipitates, and then the heavy metal precipitates are separated to obtain the inorganic matter tertiary filtrate.
The solution containing the sulfide ions in the above embodiment is sodium sulfide, and the common anion salt which obviously reduces the solubility in water is selected according to the water solubility condition of the heavy metal salt, and the selection basis is as follows: insoluble matter is slightly soluble.
The solution containing the sulfide ions in the above embodiment is sodium sulfate, and the common anion salt which obviously reduces the solubility in water is selected according to the water solubility condition of the heavy metal salt, and the selection basis is as follows: insoluble matter is slightly soluble.
In some embodiments of the invention, lime is added to the crushed solid potassium chloride feedstock containing impurities during the pretreatment process described above. In the pretreatment process, the potassium chloride raw material is detected to be acidic before feeding, lime is added into the crushed potassium chloride raw material and is fully stirred, so that acidic substances in the potassium chloride raw material are neutralized, corrosion of the potassium chloride with the acidic substances to the calcining equipment after the potassium chloride with the acidic substances enters the calcining equipment is avoided, and the service life of the calcining equipment is greatly prolonged.
In some embodiments of the present invention, the gas generated during the above-mentioned process of removing the organic impurities is alkali-washed by alkali-washing liquid. After calcination, the potassium chloride crystal also contains residual gas in the calcination equipment, and the acid gas exists in the residual gas, so that the residual gas is cleaned and neutralized through alkali washing liquid, and the pollution of the discharged gas to the environment is avoided.
In some embodiments of the invention, the above-described addition of a basic oxide or hydroxide to the alkaline wash solution.
In this embodiment, calcium oxide is added to the alkaline washing solution, and since the residual gas contains hydrogen fluoride gas, calcium fluoride precipitate and water are generated by the reaction of calcium oxide and hydrogen fluoride gas, so that the hydrogen fluoride gas is discharged into the atmosphere to cause environmental pollution.
In some embodiments of the present invention, in the crystallization separation process, the third-stage filtrate is first evaporated and crystallized, then centrifuged to obtain sodium chloride crystals and a fourth-stage filtrate, the centrifuged fourth-stage filtrate is cooled and crystallized to obtain potassium chloride solid and mother liquor, and the mother liquor is returned to the system for recrystallization separation. The components in the three-stage filtrate are basically potassium chloride, but contain a small amount of sodium chloride, a salt separation system is adopted to separate potassium chloride and sodium chloride, sodium chloride crystals in the three-stage filtrate are separated out through evaporation crystallization and are centrifugally separated to obtain four-stage filtrate, the four-stage filtrate only contains potassium chloride, high-purity potassium chloride solids are separated out through a cooling crystallization mode and are collected, and the residual mother liquor is subjected to crystallization separation operation again, so that all potassium chloride solids in the mother liquor are separated out, the potassium chloride crystallization can be completely separated, and the waste of materials is reduced.
In some embodiments of the present invention, the condensed water generated during the crystallization separation process washes the secondary filter residue and is recovered. The condensed water produced by crystallization can be recycled and the secondary filter residue is cleaned, and the cleaned secondary filter residue can be sold outside after being collected, so that the full utilization of the materials in the whole preparation process is ensured, and the preparation cost is greatly reduced.
In some embodiments of the present invention, during the pretreatment process described above, the crushed equal amount of impurity-containing potassium chloride crystals is divided into fractions for calcination. The crushed potassium chloride crystals are continuously calcined in average quantity, so that the whole calcining process is smoother, the material temperature is convenient to control, the calcining cost is reduced, and the materials with the initial calcining temperature not being reached can be returned to the furnace for continuous calcining.
In some embodiments of the invention, the size of the crushed potassium chloride solids in the pretreatment is 1mm to 3mm. The potassium chloride crystal is crushed into small particles, so that the accuracy and effect of calcination can be improved, and the potassium chloride crystal can be fully calcined.
The features and capabilities of the present invention are described in further detail below in connection with the examples.
Example 1
Pretreatment: crushing the impurity-containing potassium chloride solid, and conveying the crushed impurity-containing potassium chloride solid with the particle size of 2mm into a calciner;
removing organic impurities: calcining the crushed potassium chloride solid containing impurities in a calciner, gradually heating the potassium chloride solid to 400 ℃, and calcining for 1h to obtain calcined slag, gradually heating, decomposing and volatilizing organic matters in the potassium chloride solid, and calcining again in a high-temperature environment, wherein the calcining temperature is 1100 ℃, the calcining time is 2.5s, and the residual gas in the calciner is subjected to alkali washing by alkali washing liquid;
removing inorganic impurities: dissolving the calcined slag, adding calcium chloride, stirring to obtain a saturated mixed solution, filtering to obtain primary filtrate and primary filter residue, further washing and filtering the primary filter residue to obtain secondary filtrate and secondary filter residue, refluxing the secondary filtrate to dissolve the calcined slag again to obtain primary filtrate and primary filter residue, adding the primary filtrate into a solution containing sulfide ions, and stirring and filtering to obtain tertiary filtrate and tertiary filter residue;
crystallization separation: evaporating and crystallizing the tertiary filtrate, then centrifugally separating to obtain potassium chloride solid and mother liquor, and returning the mother liquor to the system for recrystallization and separation.
Example 2
Pretreatment: crushing the potassium chloride solid containing the impurities, and conveying the crushed potassium chloride solid containing the impurities with the particle size of 3mm into a calciner;
removing organic impurities: calcining the crushed potassium chloride solid containing impurities in a calciner, gradually heating the potassium chloride solid to 300 ℃, wherein the calcining time is 1.5h, obtaining calcined slag, gradually heating, decomposing and volatilizing organic matters in the potassium chloride solid, calcining again in a high-temperature environment, wherein the calcining temperature is 1000 ℃, the calcining time is 3s, and alkaline washing residual gas in the calciner by alkaline washing liquid;
removing inorganic impurities: dissolving the calcined slag, adding calcium chloride, stirring to obtain a saturated mixed solution, filtering to obtain primary filtrate and primary filter residue, further washing and filtering the primary filter residue to obtain secondary filtrate and secondary filter residue, refluxing the secondary filtrate to dissolve the calcined slag again to obtain primary filtrate and primary filter residue, adding the primary filtrate into a solution containing sulfide ions, and stirring and filtering to obtain tertiary filtrate and tertiary filter residue;
crystallization separation: evaporating and crystallizing the tertiary filtrate, then centrifugally separating to obtain potassium chloride solid and mother liquor, and returning the mother liquor to the system for recrystallization and separation.
Example 3
Pretreatment: crushing the potassium chloride solid containing the impurities, and conveying the crushed potassium chloride solid containing the impurities with the particle size of 1mm into a calciner;
removing organic impurities: calcining the crushed potassium chloride solid containing impurities in a calciner, gradually heating the potassium chloride solid to 600 ℃, wherein the calcining time is 0.5h, obtaining calcined slag, gradually heating, decomposing and volatilizing organic matters in the potassium chloride solid, calcining again in a high-temperature environment, wherein the calcining temperature is 1200 ℃, the calcining time is 2s, and alkaline washing residual gas in the calciner by alkaline washing liquid;
removing inorganic impurities: dissolving the calcined slag, adding calcium chloride, stirring to obtain a saturated mixed solution, filtering to obtain primary filtrate and primary filter residue, further washing and filtering the primary filter residue to obtain secondary filtrate and secondary filter residue, refluxing the secondary filtrate to dissolve the calcined slag again to obtain primary filtrate and primary filter residue, adding the primary filtrate into a solution containing sulfide ions, and stirring and filtering to obtain tertiary filtrate and tertiary filter residue;
crystallization separation: evaporating and crystallizing the tertiary filtrate, then centrifugally separating to obtain potassium chloride solid and mother liquor, and returning the mother liquor to the system for recrystallization and separation.
Example 4
Pretreatment: crushing potassium chloride solids containing impurities, weighing the crushed potassium chloride solids with the particle size of 2mm in an equivalent manner, and continuously feeding the potassium chloride solids into a calciner for calcination in a plurality of batches in sequence;
removing organic impurities: calcining the crushed potassium chloride solid containing impurities in a calciner, gradually heating the potassium chloride solid to 400 ℃, and calcining for 1h to obtain calcined slag, gradually heating, decomposing and volatilizing organic matters in the potassium chloride solid, and calcining again in a high-temperature environment, wherein the calcining temperature is 1100 ℃, the calcining time is 2.5s, and the residual gas in the calciner is subjected to alkali washing by alkali washing liquid;
removing inorganic impurities: dissolving the calcined slag, adding calcium chloride, stirring to obtain a saturated mixed solution, filtering to obtain primary filtrate and primary filter residue, further washing and filtering the primary filter residue to obtain secondary filtrate and secondary filter residue, refluxing the secondary filtrate to dissolve the calcined slag again to obtain primary filtrate and primary filter residue, adding the primary filtrate into a solution containing sulfide ions, and stirring and filtering to obtain tertiary filtrate and tertiary filter residue;
crystallization separation: evaporating and crystallizing the tertiary filtrate, then centrifugally separating to obtain potassium chloride solid and mother liquor, and returning the mother liquor to the system for recrystallization and separation.
Example 5
Pretreatment: crushing the impurity-containing potassium chloride solid, adding lime into the crushed impurity-containing potassium chloride solid with the particle size of 2mm, stirring, weighing the stirred potassium chloride solid in an equivalent amount, and continuously feeding the stirred potassium chloride solid into a calciner for calcination in a plurality of batches in sequence;
removing organic impurities: calcining the crushed potassium chloride solid containing impurities in a calciner, gradually heating the potassium chloride solid to 400 ℃, and calcining for 1h to obtain calcined slag, gradually heating, decomposing and volatilizing organic matters in the potassium chloride solid, and calcining again in a high-temperature environment, wherein the calcining temperature is 1100 ℃, the calcining time is 2.5s, and the residual gas in the calciner is subjected to alkali washing by alkali washing liquid;
removing inorganic impurities: dissolving the calcined slag, adding calcium chloride, stirring to obtain a saturated mixed solution, filtering to obtain primary filtrate and primary filter residue, further washing and filtering the primary filter residue to obtain secondary filtrate and secondary filter residue, refluxing the secondary filtrate to dissolve the calcined slag again to obtain primary filtrate and primary filter residue, adding the primary filtrate into a solution containing sulfide ions, and stirring and filtering to obtain tertiary filtrate and tertiary filter residue;
crystallization separation: evaporating and crystallizing the tertiary filtrate, then centrifugally separating to obtain potassium chloride solid and mother liquor, and returning the mother liquor to the system for recrystallization and separation.
Example 6
Pretreatment: crushing the impurity-containing potassium chloride solid, adding lime into the crushed impurity-containing potassium chloride solid with the particle size of 2mm, stirring, weighing the stirred potassium chloride solid in an equivalent amount, and continuously feeding the stirred potassium chloride solid into a calciner for calcination in a plurality of batches in sequence;
removing organic impurities: calcining the crushed potassium chloride solid containing impurities in a calciner, gradually heating the potassium chloride solid to 400 ℃, and calcining for 1h to obtain calcined slag, gradually heating, decomposing and volatilizing organic matters in the potassium chloride solid, and calcining again in a high-temperature environment, wherein the calcining temperature is 1100 ℃, the calcining time is 2.5s, and alkaline washing is carried out on residual gas in the calciner through alkaline washing liquid containing calcium oxide;
removing inorganic impurities: dissolving the calcined slag, adding calcium chloride, stirring to obtain a saturated mixed solution, filtering to obtain primary filtrate and primary filter residue, further washing and filtering the primary filter residue to obtain secondary filtrate and secondary filter residue, refluxing the secondary filtrate to dissolve the calcined slag again to obtain primary filtrate and primary filter residue, adding the primary filtrate into a solution containing sulfide ions, and stirring and filtering to obtain tertiary filtrate and tertiary filter residue;
crystallization separation: evaporating and crystallizing the tertiary filtrate, then centrifugally separating to obtain potassium chloride solid and mother liquor, and returning the mother liquor to the system for recrystallization and separation.
Example 7
Pretreatment: crushing the impurity-containing potassium chloride solid, adding lime into the crushed impurity-containing potassium chloride solid with the particle size of 2mm, stirring, weighing the stirred potassium chloride solid in an equivalent amount, and sequentially feeding the potassium chloride solid into a calciner for calcination in batches;
removing organic impurities: calcining the crushed potassium chloride solid containing impurities in a calciner, gradually heating the potassium chloride solid to 400 ℃, and calcining for 1h to obtain calcined slag, gradually heating, decomposing and volatilizing organic matters in the potassium chloride solid, and calcining again in a high-temperature environment, wherein the calcining temperature is 1100 ℃, the calcining time is 2.5s, and alkaline washing is carried out on residual gas in the calciner through alkaline washing liquid containing calcium oxide;
removing inorganic impurities: dissolving the calcined slag, adding calcium chloride, stirring to obtain a saturated mixed solution, filtering to obtain primary filtrate and primary filter residue, further washing and filtering the primary filter residue to obtain secondary filtrate and secondary filter residue, refluxing the secondary filtrate to dissolve the calcined slag again to obtain primary filtrate and primary filter residue, adding the primary filtrate into a solution containing sulfide ions, and stirring and filtering to obtain tertiary filtrate and tertiary filter residue;
crystallization separation: evaporating and crystallizing the tertiary filtrate, obtaining sodium chloride crystals and quaternary filtrate through centrifugal separation, cooling and crystallizing the quaternary filtrate after centrifugal separation to obtain potassium chloride solid and mother liquor, and returning the mother liquor to a system for recrystallization and separation.
Example 8
Pretreatment: crushing the impurity-containing potassium chloride solid, adding lime into the crushed impurity-containing potassium chloride solid with the particle size of 2.5mm, stirring, weighing the stirred potassium chloride solid in an equivalent amount, and continuously feeding the stirred potassium chloride solid into a calciner for calcination in a plurality of batches in sequence;
removing organic impurities: calcining the crushed potassium chloride solid containing impurities in a calciner, gradually heating the potassium chloride solid to 400 ℃, and calcining for 1h to obtain calcined slag, gradually heating, decomposing and volatilizing organic matters in the potassium chloride solid, and calcining again in a high-temperature environment, wherein the calcining temperature is 1100 ℃, the calcining time is 2.5s, and alkaline washing is carried out on residual gas in the calciner through alkaline washing liquid containing calcium oxide;
removing inorganic impurities: dissolving the calcined slag, adding calcium chloride, stirring to obtain a saturated mixed solution, filtering to obtain primary filtrate and primary filter residue, further washing and filtering the primary filter residue to obtain secondary filtrate and secondary filter residue, refluxing the secondary filtrate to dissolve the calcined slag again to obtain primary filtrate and primary filter residue, adding the primary filtrate into a solution containing sulfide ions, and stirring and filtering to obtain tertiary filtrate and tertiary filter residue;
crystallization separation: evaporating and crystallizing the tertiary filtrate, obtaining sodium chloride crystals and quaternary filtrate through centrifugal separation, cooling and crystallizing the quaternary filtrate after centrifugal separation to obtain potassium chloride solid and mother liquor, sending the mother liquor back to a system for recrystallization and separation, flushing secondary filter residues with condensed water generated in crystallization and separation, and recycling the secondary filter residues.
In summary, the agricultural harmless treatment process for the industrial byproduct potassium salt provided by the embodiment of the invention comprises the following steps: pretreatment: crushing the potassium chloride solid containing the impurities, and conveying the crushed potassium chloride solid containing the impurities into a calciner; removing organic impurities: calcining the crushed potassium chloride solid containing impurities in a calciner, wherein the temperature of the potassium chloride solid is gradually increased to 300-600 ℃, the calcining time is 0.5-1.5h, the calcining slag is obtained, the organic matters in the potassium chloride solid are gradually increased, decomposed and volatilized, and the calcination is carried out again in a high-temperature environment, the calcining temperature is 1000-1200 ℃, and the calcining time is 2S-3S; removing inorganic impurities: dissolving the calcined slag, adding a defluorinating agent, stirring to obtain a saturated mixed solution, filtering to obtain primary filtrate and primary filter residue, further washing and filtering the primary filter residue to obtain secondary filtrate and secondary filter residue, refluxing the secondary filtrate to dissolve the calcined slag again to obtain primary filtrate and primary filter residue, adding the heavy metal removing agent into the primary filtrate, and stirring and filtering to obtain tertiary filtrate and tertiary filter residue; crystallization separation: crystallizing the tertiary filtrate, then obtaining potassium chloride solid and mother liquor through centrifugal separation, and sending the mother liquor back to the system for recrystallization separation. Calcining the crushed potassium chloride solid containing impurities in a calciner, preparing calcined slag into a solution in a dissolving tank, adding a defluorinating agent, stirring to obtain a saturated mixed solution, filtering to obtain primary filtrate and primary filter residue, further washing and filtering the primary filter residue to obtain secondary filtrate and secondary filter residue, and returning the secondary filtrate to the primary dissolving tank; adding a heavy metal removing agent into the first-stage filtrate, stirring and filtering to obtain third-stage filtrate and third-stage filter residue; crystallization separation: and (3) evaporating and crystallizing the tertiary filtrate, and then obtaining potassium chloride solid and mother liquor through centrifugal separation, and returning the mother liquor to an evaporating crystallizer for continuous evaporation.
The method has the advantages that the effect of calcining the impurity-containing potassium chloride solid can be effectively improved by crushing the impurity-containing potassium chloride solid into particles, the potassium chloride solid particles can be fully heated and calcined and organic matters in the impurities can be separated, the calcined slag after the internal organic matters are burnt or carbonized is calcined under the high-temperature aerobic condition of the materials, the calcined slag is added with different treatment medicaments to separate and filter inorganic matters in the calcined slag, the cost is low, the inorganic matters are separated by adding different treatment medicaments, the separation effect on the inorganic matters is comprehensive and efficient, the solute component in the filtrate after the inorganic matters is separated is basically potassium chloride, and the high-purity potassium chloride crystal is prepared by a crystallization treatment mode.
The invention increases the self-supporting rate of the domestic potassium salt, has low production cost, is far lower than the price of similar products in the market, brings objective economic benefit to investors, and is beneficial to large-scale popularization.
The embodiments described above are some, but not all embodiments of the invention. The detailed description of the embodiments of the invention is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Claims (6)
1. An agricultural harmless treatment process for industrial byproduct potassium salt is characterized by comprising the following steps:
pretreatment: crushing the potassium chloride solid containing the impurities, adding lime into the crushed potassium chloride solid containing the impurities, and then sending the crushed potassium chloride solid into a calciner;
removing organic impurities: calcining the crushed potassium chloride solid containing impurities in a calciner, wherein the temperature of the potassium chloride solid is gradually increased to 300-600 ℃, the calcining time is 0.5-1.5h, the calcining slag is obtained, the organic matters in the potassium chloride solid are gradually increased, decomposed and volatilized, and the calcination is carried out again in a high-temperature environment, the calcining temperature is 1000-1200 ℃, and the calcining time is 2S-3S; performing alkaline washing on the generated gas through alkaline washing liquid, wherein alkaline oxide or hydroxide is added into the alkaline washing liquid;
removing inorganic impurities: dissolving the calcined slag, adding a defluorinating agent, stirring to obtain a saturated mixed solution, filtering to obtain primary filtrate and primary filter residue, further washing and filtering the primary filter residue to obtain secondary filtrate and secondary filter residue, refluxing the secondary filtrate to dissolve the calcined slag again to obtain primary filtrate and primary filter residue, adding the heavy metal removing agent into the primary filtrate, and stirring and filtering to obtain tertiary filtrate and tertiary filter residue;
crystallization separation: crystallizing the tertiary filtrate, then obtaining potassium chloride solid and mother liquor through centrifugal separation, and sending the mother liquor back to the system for recrystallization separation, and flushing the secondary filter residue with the produced condensate water and recycling.
2. The agricultural harmless treatment process of industrial byproduct potassium salt according to claim 1, wherein the fluorine removing agent is one of calcium chloride, magnesium chloride or calcium magnesium salt.
3. The agricultural harmless treatment process of industrial byproduct potassium salt according to claim 1, wherein the heavy metal removing agent is an anionic salt solution capable of generating heavy metal salt which is difficult to dissolve in water.
4. The agricultural harmless treatment process of the industrial byproduct potassium salt according to claim 1, wherein in the crystallization separation process, the tertiary filtrate is subjected to cooling crystallization, sodium chloride crystals and quaternary filtrate are obtained through centrifugal separation, the quaternary filtrate after centrifugal separation is subjected to evaporation crystallization to obtain potassium chloride solid and mother liquor, and the mother liquor is returned to the system for recrystallization separation.
5. The agricultural harmless treatment process for industrial by-product potassium salt according to claim 1, wherein in the pretreatment process, the crushed potassium chloride crystal containing impurities is continuously calcined in average amount.
6. The agricultural harmless treatment process of the industrial byproduct potassium salt according to claim 2, wherein the size of the crushed potassium chloride solid in the pretreatment is 1mm-3mm.
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