Production process for preparing potassium chloride by using underground native carnallite ore

Abstract

A production process for preparing potassium chloride by using underground native carnallite ore comprises the following steps: carrying out primary crushing on the underground native carnallite ore, combining a material obtained by carrying out secondary crushing on an oversize material with an undersize material, conveying the combined material to a decomposer or a crystallizer, adding a beneficiation reagent into decomposed slurry or underflow slurry of the crystallizer, and carrying out roughing, roughing concentrate K1 and roughing tailings T1 are obtained; roughing tailings T1 are conveyed to a thickener, overflow of the thickener is collected and then returns to a decomposing tank for size mixing or flotation size mixing, and underflow of the thickener is subjected to ore grinding operation; materials discharged by the mill are conveyed to middling flotation operation to obtain middling flotation concentrate K2 and flotation tailings T2, the middling flotation concentrate K2 and decomposed slurry of the decomposing tank are subjected to roughing operation together, and roughing concentrate K1 is obtained; and the roughing concentrate K1 is subjected to secondary concentration to obtain crude potassium slurry K4, the crude potassium slurry K4 is filtered to obtain a crude potassium filter cake K5, and the crude potassium filter cake K5 is washed and filtered to obtain a potassium chloride wet material product. The product is high in recovery rate and proper in particle size.

Description

Technical Field

[0001] This invention relates to the field of potassium chloride product preparation, and particularly to a production process for producing potassium chloride using underground primary carnallite ore. Background Technology

[0002] Currently, carnallite ore is generally processed into agricultural potassium chloride fertilizer using decomposition direct flotation or decomposition-crystallization direct flotation processes, as disclosed in Chinese patent applications CN116161680A, CN118637642A, and CN101982412A. These processes involve grinding the raw ore before decomposition or crystallization. Carnallite is easily decomposed, producing a large number of fine crystals, which hinders crystal growth during recrystallization. Secondly, all materials enter the grinding process, resulting in high energy consumption. Furthermore, over-grinding of sodium chloride during the grinding stage leads to high impurity content in the flotation froth, resulting in low flotation efficiency. Summary of the Invention

[0003] (a) Technical problems to be solved In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a simple and high-yield production process for producing potassium chloride from underground primary carnallite ore.

[0004] (II) Technical Solution To achieve the above objectives, this invention provides a production process for producing potassium chloride using underground primary carnallite ore, comprising the following steps: first crushing the underground primary carnallite ore, then screening the material to obtain oversize material and undersize material, then combining the oversize material with the undersize material after secondary crushing and conveying them to a decomposition tank, at which point the particle size of the material is P95≤12mm. Add fresh water, potassium-rich mother liquor, and slurry conditioning mother liquor to the decomposition tank or crystallizer for cold decomposition and crystallization. The mass concentration of the slurry discharged from the decomposition tank or crystallizer is less than 30%. Mineral processing reagents are added to the decomposition slurry or the bottom flow slurry of the crystallizer for roughing to obtain roughing concentrate K1 and roughing tailings T1. The roughing tailings T1 are conveyed to the thickener. The overflow from the thickener is collected and returned to the decomposer for pulp conditioning or flotation pulp conditioning. The underflow from the thickener is sent to the grinding operation. The mass concentration of the underflow from the thickener is controlled at 50-65%. In the grinding operation, the grinding output particle size is F80≤1mm. After adding flotation reagents to the mill discharge and adjusting the slurry, it is transported to the middlings flotation machine to obtain middlings flotation concentrate K2 and flotation tailings slurry. After filtering, the flotation tailings slurry is used to obtain tailings filter cake T2 and flotation mother liquor L2. Part of the flotation mother liquor L2 is collected through the mother liquor collection tank, and part is returned to the system for use. The middlings flotation concentrate K2 is returned to the decomposition slurry or the crystallizer underflow slurry for roughing. The rough concentrate K1 is processed through a first cleaning operation to obtain a first cleaning foam K3 and a first cleaning tailings T3. The first cleaning foam K3 is processed through a second cleaning operation to obtain crude potassium slurry K4 and a second cleaning tailings T4. The first cleaning tailings T3 are returned to the second roughing operation, and the second cleaning tailings T4 are returned to the first cleaning operation. After filtration of crude potassium slurry K4, crude potassium filter cake K5 and mother liquor L1 are obtained. Crude potassium filter cake K5 is washed, filtered, dried and dehydrated to obtain potassium chloride product. The purity of potassium chloride product is greater than or equal to 95%, and the product particle size F50 is greater than 100 micrometers.

[0005] In one embodiment, the underground primary carnallite deposit includes carnallite content exceeding 50%, potassium halite 0.87%~3.76%, halite 39.3%~40.91%, gypsum 0.34%~0.49%, calcium carnallite 0.32%~1.03%, and hydrated magnesium chloride 0%~0.99%.

[0006] In one embodiment, the potassium-rich mother liquor contains K + The content is 6.5% to 11%.

[0007] In one embodiment, the first crushing process results in a raw ore particle size of P80 of 15mm to 20mm.

[0008] In one embodiment, after the first crushing, the material is screened to obtain oversize material and undersize material, with a screening particle size of 8mm~12mm.

[0009] In one embodiment, the flotation reagent is a mixture of octadecylamine hydrochloride and No. 2 oil, or a potassium salt three-in-one flotation reagent.

[0010] In one embodiment, the particle size F50 of the potassium chloride product is 100-200 micrometers.

[0011] (III) Beneficial Effects The beneficial effects of this invention are as follows: In the method of this invention, the mineral does not need to undergo grinding before decomposition. It enters the decomposition operation after secondary crushing, avoiding grinding of carnallite ore, greatly reducing the energy consumption of the device, reducing energy consumption by at least 40%. At the same time, the dry feeding into the decomposition process helps to control the decomposition rate of carnallite ore and the number of potassium chloride crystal nuclei in the crystallizer. The potassium chloride crystals grow by utilizing the nucleation rate. The slurry obtained from the decomposition of carnallite is directly sent to flotation, avoiding grinding of the grown potassium chloride crystals, which effectively protects the potassium chloride crystals. After the tailings from the first roughing process are concentrated, they are sent to grinding to refine the coarse potassium rock ore particles, and then sent to flotation to recover the potassium rock ore and coarse particles of decomposed potassium chloride from the original ore. Combining decomposition and flotation, supplemented by staged crushing and mother liquor recycling, forms a highly efficient, stable and synergistic recovery system. The recovery rate of potassium chloride has been improved, with the obtained potassium chloride mass fraction exceeding 95% and the potassium chloride recovery rate exceeding 78%. The product particle size F50 is greater than 100 micrometers. The larger particle size helps to reduce dust loss and agglomeration during storage and transportation. It also better meets the particle size requirements of certain fertilizers (such as blended fertilizers and BB fertilizers), thus broadening the scope of market applications. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of a production process for producing potassium chloride from underground primary carnallite ore, as one embodiment. Detailed Implementation

[0013] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below through specific embodiments.

[0014] Example 1 (1) The primary carnallite deposit in a potash mine in Vientiane, Laos (the main components of the raw ore are KCl 18.35%, NaCl 39.3%, MgCl2 19.16%, CaSO4 0.34%, CaCl2 0.24%, and water-insoluble matter 0.61%) was collected. The mineral composition is carnallite 54.37%, potash 3.76%, halite 39.30%, gypsum 0.34%, chrysotile 0.32%, and magnesia hygroscopica 0.99%.

[0015] (2) The mixed raw materials are crushed for the first time. The crusher is a heavy ring hammer crusher. The particle size of the crushed raw ore is P80, which is 20mm. After the first crushing, the material is screened to obtain the oversize material and the undersize material. The screening particle size is 12mm. The oversize material is crushed for the second time and then combined with the undersize material and transported to the decomposition operation. At this time, the particle size of the material is P95≤12mm.

[0016] (3) The crushed material is transported to the decomposition tank. Fresh water and potassium-rich mother liquor (K+ content in the mother liquor is 6.5~11%) and slurry-adjusting mother liquor are added to the decomposition tank. The volume of the decomposition tank is sufficient to allow the material to stay for 50 minutes. The mass concentration of the carnallite decomposition slurry discharged from the decomposition tank is controlled at 30%.

[0017] (4) After decomposition, the slurry is added with flotation reagents and then fed by gravity or pump to a flotation machine for roughing to obtain roughing concentrate K1 and roughing tailings T1. The flotation reagents are a mixture of octadecylamine hydrochloride and No. 2 oil.

[0018] (5) The roughing tailings T1 flow by gravity to the outdoor thickener. The overflow of the thickener is collected and returned to the decomposition slurry or flotation slurry. The underflow of the thickener is used for grinding operations. The mass concentration of the underflow of the thickener is controlled at 50~65%. The main substances are a mixture of halite and a small amount of potassium rock.

[0019] (6) The grinding discharge particle size is controlled by the amount of grinding media added to the mill. The grinding discharge particle size is F80≤1mm. After adding flotation reagents to the mill discharge and adjusting the slurry, it is sent to the middlings flotation machine for flotation. The tailings from the flotation machine are sent to a belt filter to obtain tailings T2 and mother liquor. The middlings flotation concentrate and decomposed slurry are sent to the roughing operation to obtain roughing concentrate K1. A ball mill is used.

[0020] (7) The rough concentrate K1 is processed through a primary cleaning operation to obtain primary cleaning foam K3 and primary cleaning tailings T3. The primary cleaning foam K3 is processed through a secondary cleaning operation to obtain crude potassium slurry K4 and secondary cleaning tailings T4. The primary cleaning tailings T3 are returned to the primary rougher, and the secondary cleaning tailings T4 are returned to the primary cleaner. The thickener overflow mother liquor is used for slurry preparation in the cleaning operation.

[0021] (8) After filtering the crude potassium slurry K4, crude potassium filter cake K5 and mother liquor L1 are obtained. The crude potassium filter cake K5 is washed, filtered, dried and dehydrated to obtain potassium chloride product (mass percentage content 95%). The product particle size F50 is about 100 micrometers.

[0022] Example 2 (1) The primary carnallite deposit in the underground of a potash mine in Khammouane, Laos (the main components of the raw ore are KCl 13.55%, NaCl 42.57%, MgCl2 18.80%, CaSO4 0.30%, CaCl2 1.3875%, and water-insoluble matter 1.53%) was collected. The mineral composition is carnallite 54.89%, potash 13.55%, halite 42.59%, gypsum 0.34%, effusive 0.32%, and magnesia hydrate 0.99%.

[0023] (2) The mixed raw materials are crushed for the first time. The crusher is a heavy ring hammer crusher. The particle size of the crushed raw ore is P80, which is 20mm. After the first crushing, the material is screened to obtain the oversize material and the undersize material. The screening particle size is 12mm. The oversize material is crushed for the second time and then combined with the undersize material and transported to the decomposition operation. At this time, the particle size of the material is P95≤12mm.

[0024] (3) The crushed material is transported to the crystallizer. Fresh water and potassium-rich mother liquor (K+ content in the mother liquor is 6.5~11%) and slurry conditioning mother liquor are added to the crystallizer. The volume of the crystallizer is sufficient for the material to stay for 120 minutes. The mass concentration of the carnallite decomposition slurry discharged from the crystallizer is controlled at 30%.

[0025] (4) After adding flotation reagents to the bottom slurry of the crystallizer, it is either gravity-fed or pumped to the flotation machine for roughing to obtain roughing concentrate K1 and roughing tailings T1, respectively. The flotation reagents are a mixture of octadecylamine hydrochloride and No. 2 oil.

[0026] (5) The roughing tailings T1 flow by gravity to the outdoor thickener. The overflow of the thickener is collected and returned to the crystallization slurry or flotation slurry. The underflow of the thickener is used for grinding operations. The mass concentration of the underflow of the thickener is controlled at 50~65%.

[0027] (6) The grinding discharge particle size is controlled by the amount of grinding media added to the mill. The grinding discharge particle size is F80≤1mm. After adding flotation reagents to the mill discharge and adjusting the slurry, it is sent to the middlings flotation machine for flotation. The tailings from the middlings flotation machine are sent to a belt filter to obtain tailings T2 and mother liquor L2. The middlings flotation concentrate T2 obtained from the middlings flotation machine is sent to the roughing operation together with the crystallizer slurry to obtain roughing concentrate K1. A rod mill is used.

[0028] (7) The rough concentrate K1 is processed through a primary cleaning operation to obtain primary cleaning foam K3 and primary cleaning tailings T3. The primary cleaning foam K3 is processed through a secondary cleaning operation to obtain crude potassium slurry K4 and secondary cleaning tailings T4. The primary cleaning tailings T3 are returned to the primary rougher, and the secondary cleaning tailings T4 are returned to the primary cleaner. The thickener overflow mother liquor is used for slurry preparation in the cleaning operation.

[0029] (8) After filtering the crude potassium slurry K4, crude potassium filter cake K5 and mother liquor L1 are obtained. K5 is washed, filtered, dried and dehydrated to obtain potassium chloride product (mass percentage content 95%). The product particle size F50 is about 190 micrometers and the recovery rate is 79%.

[0030] Example 3 (1) The underground primary carnallite ore of a potash mine in Khammouane, Laos (the main components of the raw ore are KCl 16.53%, NaCl 41.21%, MgCl2 17.18%, CaSO4 0.29%, and water-insoluble matter 0.93%) was collected. The mineral composition is carnallite 50.2%, potash 3.08%, halite 40.91%, gypsum 0.29%, and H2O 5.52%.

[0031] (2) The mixed raw materials are crushed for the first time. The crusher is a heavy ring hammer crusher. The particle size of the crushed raw ore is P80 of 12mm. After the first crushing, the material is screened to obtain the oversize material and undersize material. The screening particle size is 6mm. The oversize material is crushed for the second time and then combined with the undersize material and transported to the decomposition and crystallization unit. At this time, the particle size of the material is P90≤8mm.

[0032] (3) The crushed material is transported to the crystallizer. Fresh water and potassium-rich mother liquor (K+ content in the mother liquor is 6.5~11%) and tailings mother liquor are added to the crystallizer. The volume of the crystallizer is sufficient to allow the material to stay for 120 minutes. The mass concentration of the discharge from the bottom flow of the crystallizer is controlled at 32%.

[0033] The crystallization process can be either single-stage or two-stage. If two-stage crystallization is used, the ratio of feed rates for single-stage and two-stage crystallization is 7:3. The overflow from single-stage crystallization is collected and partially returned to single-stage crystallization for slurry preparation, and partially sent to the mother liquor evaporation unit to produce secondary carnallite. The overflow from two-stage crystallization is sent to single-stage crystallization, and the underflow slurry from two-stage crystallization is sent to flotation.

[0034] (4) After adding mineral processing reagents to the slurry from the crystallization bottom flow for slurry conditioning, it is either gravity-fed or pumped to a flotation machine for roughing to obtain roughing concentrate K1 and roughing tailings T1, respectively. The mineral processing reagents are a mixture of octadecylamine hydrochloride and No. 2 oil, or a potassium salt three-in-one flotation reagent.

[0035] (5) The roughing tailings T1 are pumped to the thickener. The overflow from the thickener is collected and returned to the decomposer or flotation slurry, and the underflow from the thickener is sent to the grinding operation. The concentration of the underflow from the thickener is controlled at 50-65%.

[0036] (6) The grinding discharge particle size is controlled by the amount of grinding media added to the mill. The grinding discharge particle size is F90≤1mm. After adding flotation reagents to the mill discharge and adjusting the slurry, it is conveyed to the middlings flotation column for flotation. The tailings from the middlings flotation column are conveyed to a belt filter to obtain tailings T2 and mother liquor L24. The middlings flotation concentrate K2 and the crystallizer slurry are conveyed together to the roughing operation. A rod mill is used.

[0037] (7) The rough concentrate K1 is processed through a primary cleaning operation to obtain primary cleaning foam K3 and primary cleaning tailings T3. The primary cleaning foam K3 is processed through a secondary cleaning operation to obtain crude potassium slurry K4 and secondary cleaning tailings T4. The primary cleaning tailings T3 are returned to the primary rougher, and the secondary cleaning tailings T4 are returned to the primary cleaner. The thickener overflow mother liquor is used for slurry preparation in the cleaning operation.

[0038] (8) After filtering the crude potassium slurry K4, crude potassium filter cake K5 and mother liquor L1 are obtained. K5 is washed, filtered, dried and dehydrated to obtain potassium chloride product (mass percentage content 95%). The product particle size F50 is about 137 micrometers.

[0039] Comparative example: (1) The underground primary carnallite ore of a potash mine in Khammouane, Laos (the main components of the raw ore are KCl 16.53%, NaCl 41.21%, MgCl2 17.18%, CaSO4 0.29%, and water-insoluble matter 0.93%) was collected. The mineral composition is carnallite 50.2%, potash 3.08%, halite 40.91%, gypsum 0.29%, and H2O 5.52%.

[0040] (2) The mixed raw materials are crushed for the first time. The crusher is a heavy ring hammer crusher. The particle size of the crushed raw ore is P80 = 20mm. After the material is crushed, it is slurried with L2 to a concentration of 55% and then fed into the rod mill. The mill discharge is F90 = 1mm.

[0041] (3) The discharge from the mill is conveyed to the crystallizer. Fresh water and potassium-rich mother liquor (the K+ content in the mother liquor is 6.5~11%, and the main substance is fresh water) and tailings mother liquor are added to the crystallizer. The volume of the crystallizer is sufficient to allow the material to stay for 120 minutes. The mass concentration of the discharge from the bottom flow of the crystallizer is controlled at 32%.

[0042] The crystallization process can be either single-stage or two-stage. If two-stage crystallization is used, the ratio of feed rates for single-stage and two-stage crystallization is 7:3. The overflow from single-stage crystallization is collected and partially returned to single-stage crystallization for slurry preparation, and partially sent to the mother liquor evaporation unit to produce secondary carnallite. The overflow from two-stage crystallization is sent to single-stage crystallization, and the underflow slurry from two-stage crystallization is sent to flotation.

[0043] (4) After adding mineral processing reagents to the slurry from the crystallization underflow for conditioning, it is either gravity-fed or pumped to a flotation machine for primary roughing to obtain primary roughing concentrate K1 and primary roughing tailings T1. The mineral processing reagents are a mixture of octadecylamine hydrochloride and No. 2 oil.

[0044] (5) The tailings T1 from the first roughing process enter the scavenging process to obtain scavenging foam and scavenging tailings T2. The scavenging foam is the middlings M1. The middlings M1 is returned to the first roughing process.

[0045] (6) The primary roughing concentrate K1 is processed through a primary cleaning operation to obtain primary cleaning foam K3 and primary cleaning tailings T3. The primary cleaning foam K3 is processed through a secondary cleaning operation to obtain crude potassium slurry K4 and secondary cleaning tailings T4. The primary cleaning tailings T3 are returned to the primary roughing operation, and the secondary cleaning tailings T4 are returned to the primary cleaning operation. The thickener overflow mother liquor is used for slurry preparation in the cleaning operation.

[0046] (8) After filtering the crude potassium slurry K4, crude potassium filter cake K5 and mother liquor L1 are obtained. After filtering the scavenged tailings T2, tailings filter cake T2 and mother liquor L2 are obtained. K5 is washed, filtered, dried and dehydrated to obtain potassium chloride product (mass percentage content 95%). The product particle size F 50 It is approximately 89 micrometers.

[0047] In the comparative example, all materials were fed into a mill, which was relatively large and had high energy consumption. In addition, the carnallite ore in the grinding section was decomposed prematurely, resulting in small crystal particle size and powdery product.

[0048] In the description of this specification, the terms "one embodiment," "some embodiments," "embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A production process for producing potassium chloride from underground primary carnallite ore, characterized in that, include: The underground primary carnallite ore is first crushed. After the first crushing, the material is screened to obtain oversize material and undersize material. The oversize material is then crushed in the second stage and the material obtained is combined with the undersize material and transported to the decomposition tank. At this time, the particle size of the material is P95≤12mm. Add fresh water, potassium-rich mother liquor, and slurry conditioning mother liquor to the decomposition tank or crystallizer for cold decomposition and crystallization. The mass concentration of the slurry discharged from the decomposition tank or crystallizer is less than 30%. Mineral processing reagents are added to the decomposition slurry or the bottom flow slurry of the crystallizer for roughing to obtain roughing concentrate K1 and roughing tailings T1. The roughing tailings T1 are conveyed to the thickener. The overflow from the thickener is collected and returned to the decomposer for pulp conditioning or flotation pulp conditioning. The underflow from the thickener is sent to the grinding operation. The mass concentration of the underflow from the thickener is controlled at 50-65%. In the grinding operation, the grinding output particle size is F80≤1mm. After adding flotation reagents to the mill discharge and adjusting the slurry, it is transported to the middlings flotation machine to obtain middlings flotation concentrate K2 and flotation tailings slurry. After filtering, the flotation tailings slurry is used to obtain tailings filter cake T2 and flotation mother liquor L2. Part of the flotation mother liquor L2 is collected through the mother liquor collection tank, and part is returned to the system for use. The middlings flotation concentrate K2 is returned to the decomposition slurry or the crystallizer underflow slurry for roughing. The rough concentrate K1 is processed through a first cleaning operation to obtain a first cleaning foam K3 and a first cleaning tailings T3. The first cleaning foam K3 is processed through a second cleaning operation to obtain crude potassium slurry K4 and a second cleaning tailings T4. The first cleaning tailings T3 are returned to the second roughing operation, and the second cleaning tailings T4 are returned to the first cleaning operation. After filtration of crude potassium slurry K4, crude potassium filter cake K5 and mother liquor L1 are obtained. Crude potassium filter cake K5 is washed, filtered, dried and dehydrated to obtain potassium chloride product. The purity of potassium chloride product is greater than or equal to 95%, and the product particle size F50 is greater than 100 micrometers.

2. The production process for producing potassium chloride from underground primary carnallite ore according to claim 1, characterized in that, The underground primary carnallite deposits include carnallite content exceeding 50%, potassium halite 0.87%~3.76%, halite 39.3%~40.91%, gypsum 0.34%~0.49%, calcium carnallite 0.32%~1.03%, and hydrated magnesium chloride 0%~0.99%.

3. The production process for producing potassium chloride from underground primary carnallite ore according to claim 2, characterized in that, K in potassium-rich mother liquor + The content is 6.5% to 11%.

4. The production process for producing potassium chloride from underground primary carnallite ore according to claim 1, characterized in that, The first crushing process resulted in a raw ore particle size of 15mm~20mm after crushing (P80).

5. The production process for producing potassium chloride from underground primary carnallite ore according to claim 4, characterized in that, After the first crushing, the material is screened to obtain oversize and undersize material, with a screening particle size of 8mm~12mm.

6. The production process for producing potassium chloride from underground primary carnallite ore according to claim 1, characterized in that, The flotation reagent is a mixture of octadecylamine hydrochloride and No. 2 oil, or a potassium salt three-in-one flotation reagent.

7. The production process for producing potassium chloride from underground primary carnallite ore according to claim 1, characterized in that, The particle size F50 of potassium chloride products is 100~200 micrometers.

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