Method for removing calcium through reverse flotation of carnallite and process for producing potassium chloride through reverse flotation cold crystallization

Abstract

The invention provides a method for removing calcium through reverse flotation of carnallite and a process for producing potassium chloride through reverse flotation cold crystallization. The method for removing calcium through reverse flotation of carnallite comprises the steps that a precipitant solution is added into saturated balanced brine ore pulp containing carnallite particles to precipitate Ca < 2 + >, then collecting reverse flotation is conducted on NaCl and CaSO4 through a NaCl collecting agent and a CaSO4 collecting agent, and carnallite concentrate is obtained; wherein the CaSO4 collecting agent comprises 60 to 80 weight percent of alkyl ether amine and 20 to 40 weight percent of modified fatty acid. According to the method, Ca < 2 + > is removed through the precipitant, then NaCl and CaSO4 are subjected to collecting and reverse flotation through the NaCl collecting agent and the CaSO4 collecting agent, the carnallite concentrate is obtained, production equipment cannot be blocked in the process of preparing the potassium chloride product, the quality of the potassium chloride product can be improved, the yield of the potassium chloride product can be increased, meanwhile, the productivity can be improved, and the production cost can be reduced.

Description

Technical Field

[0001] The invention relates to the field of salt lake chemical industry, and in particular to a method for removing calcium by reverse flotation of carnallite and a process for producing potassium chloride by reverse flotation cold crystallization. Background Art

[0002] With the continuous exploitation of salt lake brine, the amount of intercrystalline brine is decreasing, and the quality of brine is declining year by year, with a lot of calcium impurities entrained in it. In order to ensure the amount of brine mined, the solvent configured with old brine is injected into the solid ore layer through solid-liquid conversion technology, but the old brine contains a lot of calcium impurities, which will enter the original brine during the solid-liquid conversion process. In addition, during the salt field drying process, the bottom of the salt pond is directly mud, and some fine mud is easily entrained into the carnallite. These fine muds entrained into the carnallite "contribute" a lot of calcium impurities. The above reasons have jointly led to the problem of high calcium impurity content in the original brine in some brine mining areas of the salt lake. It can be foreseen that with the continuous exploitation and use of salt lake brine, the problem of potassium salt mine depletion will become more prominent in the future, and the content of calcium impurities will continue to increase.

[0003] In the production process of potassium salt, Ca 2+ The presence of will inevitably affect the capture behavior of the collector on NaCl, and ultimately affect the yield and purity of the KCl product. The CaSO4 impurities present in the brine can combine with water molecules in the brine to form slightly soluble CaSO4·2H2O particles, which will be mixed in the carnallite during the brine mining process and enter the subsequent potash fertilizer production and processing system. Except for a small amount of these slightly soluble granular impurities that are discharged with the mother liquor through washing, concentration, centrifugal separation and other processes, 80-90% of the CaSO4 cannot be removed and eventually enters the potassium chloride product, reducing the purity of the potassium chloride product. In particular, when the mass content of CaSO4·2H2O in carnallite is greater than 5%, it will cause blockage to the production equipment, affect the production process, and even cause shutdown for maintenance. In the process of producing potassium chloride products using high-calcium carnallite raw materials, the CaSO4 impurities damage the production equipment on the one hand, increasing the maintenance costs of the equipment, and on the other hand, the shutdown for maintenance affects normal production and reduces production capacity.

[0004] Therefore, Ca 2+ Impurities and CaSO4 impurities will reduce the quality and yield of potassium chloride products, and even damage production equipment, reduce production capacity, increase production costs, and damage production benefits. How to eliminate the impact of calcium impurities on salt field systems and potash fertilizer production and processing systems is the key to improving the quality of potassium chloride products. The development of economically feasible calcium removal technology can improve product quality and increase production utilization, which is of great significance. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for removing calcium by reverse flotation of carnallite and a process for producing potassium chloride by reverse flotation cold crystallization, so as to solve the problem that the quality and yield of the potassium chloride product produced are low due to the presence of calcium impurities in the prior art.

[0006] In order to achieve the above object, according to one aspect of the present invention, a method for removing calcium by reverse flotation of carnallite is provided, the method comprising: adding a precipitant solution to a saturated equilibrium brine slurry containing carnallite particles to remove calcium; 2+ The process comprises the following steps: precipitation, and then collecting and reverse flotating NaCl and CaSO4 with NaCl collector and CaSO4 collector to obtain carnallite concentrate; wherein, the CaSO4 collector comprises 60-80% alkyl ether amine and 20-40% modified fatty acid by mass percentage.

[0007] Furthermore, the particle size of the carnallite particles in the saturated equilibrium brine slurry containing the carnallite particles is ≤1 mm.

[0008] Furthermore, the mass concentration of the saturated equilibrium brine slurry containing carnallite particles is 30-70%.

[0009] Furthermore, the preparation method of the saturated balanced brine slurry containing carnallite particles includes: mixing the carnallite precipitated from the salt field with the saturated balanced brine, first scrubbing it to pre-remove CaSO4, and then screening the particle size to obtain the saturated balanced brine slurry containing the carnallite particles.

[0010] Furthermore, a scrubbing machine is used for scrubbing treatment, and the scrubbing treatment time is preferably 10-20 minutes.

[0011] Furthermore, the Ca 2+ The mass content of is 1.2-3.0%, and the mass content of CaSO4 is 4.0-7.0%.

[0012] Furthermore, the precipitant in the precipitant solution includes at least one of sodium sulfate or sodium bisulfate.

[0013] Furthermore, the mass ratio of the precipitant in the precipitant solution to the carnallite particles in the saturated equilibrium brine slurry containing the carnallite particles is 1:10-20.

[0014] Furthermore, the molar concentration of the precipitant is 1-3 mol / L.

[0015] Furthermore, stirring is performed while adding the precipitant, the stirring speed is 80-100 r / min, and the stirring time is 1-30 min.

[0016] Further, the NaCl collector comprises alkylmorpholine, preferably dodecylmorpholine.

[0017] Furthermore, the dosage of NaCl collector is 80-120 g / t.

[0018] Furthermore, the dosage of CaSO4 collector is 100-300g / t.

[0019] Furthermore, the alkyl ether amine was purchased from Kunming Liangfan Technology Co., Ltd., model LF-24.

[0020] Furthermore, the modified fatty acid was purchased from Guangzhou Zelong Chemical Technology Co., Ltd., model number ZR-101.

[0021] To achieve the above object, according to another aspect of the present invention, a process for producing potassium chloride by reverse flotation cold crystallization is provided, which comprises the method for removing calcium by reverse flotation of carnallite provided in the first aspect.

[0022] Furthermore, the process for producing potassium chloride by reverse flotation cold crystallization comprises: decomposing and crystallizing the carnallites concentrate to obtain a potassium chloride product; wherein the carnallites concentrate is the carnallites concentrate obtained by the method for removing calcium by reverse flotation of carnallites provided in the first aspect above.

[0023] The present invention provides a method for removing calcium by reverse flotation of carnallite, wherein a precipitant is first added to a saturated equilibrium brine slurry containing carnallite particles to remove calcium. 2+ It is removed from the brine, and then the NaCl and CaSO4 are captured and reverse floated by NaCl collectors and CaSO4 collectors to obtain carnallite concentrate. Therefore, the carnallite concentrate will not block the production equipment when used as a raw material to prepare potassium chloride products, and can effectively improve the quality and yield of potassium chloride products, and is also conducive to increasing production capacity and reducing production costs. DETAILED DESCRIPTION

[0024] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0025] As analyzed in the background technology of this application, with the continuous development and use of salt lake brine, the calcium impurity content is also increasing. 2+The removal is mainly based on the purification of brine before lithium extraction, mainly including chemical precipitation, physical calcium removal, brine addition, ion exchange, solvent extraction, electrochemical method and adsorption removal, etc. However, most of these methods are based on the need for impurity removal before lithium extraction, and the brine treatment volume is small. It is not economical to use these methods to directly remove calcium from the raw brine, and it is not easy to implement in terms of process operation. There are existing reports at home and abroad on the problem of CaSO4 impurities in carnallite ore. In the early days, domestic researchers developed CaSO4 inhibitors for the high calcium content of raw materials in the "cold decomposition-positive flotation" process. Most of them are inhibitors such as gum, dextrin, and carboxymethyl cellulose. They are only applicable to positive flotation processes and have poor inhibitory effects. In order to solve this problem, the present application provides a method for removing calcium by reverse flotation of carnallite and a process for producing potassium chloride by reverse flotation cold crystallization.

[0026] In a first typical embodiment of the present application, a method for removing calcium by reverse flotation of carnallite is provided, the method comprising: adding a precipitant to a saturated equilibrium brine slurry containing carnallite particles to remove calcium 2+ The process comprises the following steps: precipitation, and then collecting and reverse flotating NaCl and CaSO4 with NaCl collector and CaSO4 collector to obtain carnallite concentrate; wherein, the CaSO4 collector comprises 60%-80% alkyl ether amine and 20-40% modified fatty acid by mass percentage.

[0027] The present application provides a method for removing calcium by reverse flotation of carnallite, wherein a precipitant is first added to a saturated equilibrium brine slurry containing carnallite particles to remove calcium. 2+ It is removed from the brine, and then the NaCl and CaSO4 are captured and reverse floated by NaCl collectors and CaSO4 collectors to obtain carnallite concentrate. Therefore, the carnallite concentrate will not block the production equipment when used as a raw material to prepare potassium chloride products, and can effectively improve the quality and yield of potassium chloride products, and is also conducive to increasing production capacity and reducing production costs.

[0028] In the CaSO4 collector used in the present application, the mass content of alkyl ether amine is 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78%, 80% or a range consisting of any two numerical values; the mass content of modified fatty acid is 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40% or a range consisting of any two numerical values.

[0029] In the present application, the alkyl ether amine is a commonly used alkyl ether amine in the art, and the specific manufacturer and model are not limited. For example, the alkyl ether amine is purchased from Kunming Liangfan Technology Co., Ltd., and the model is LF-24.

[0030] In the present application, the modified fatty acid is a commonly used modified fatty acid in the art, and the specific manufacturer and model are not limited. For example, the modified fatty acid is purchased from Guangzhou Zelong Chemical Technology Co., Ltd., model ZR-101.

[0031] In order to further improve the reverse flotation effect of CaSO4, the preferred dosage of CaSO4 collector is 100-300 g / t, such as 100 g / t, 120 g / t, 150 g / t, 180 g / t, 200 g / t, 220 g / t, 250 g / t, 280 g / t, 300 g / t or a range value consisting of any two values.

[0032] It should be noted that "the dosage of CaSO4 collector is 100-300g / t" means that 100-300g of CaSO4 collector needs to be added to each ton of carnallite particles.

[0033] In order to further improve the reverse flotation effect of NaCl and CaSO4, the particle size (maximum particle size) of the carnallite particles in the saturated equilibrium brine slurry containing carnallite particles is preferably ≤1 mm.

[0034] In order to further improve the production capacity and the removal rate of calcium impurities, the mass concentration of the saturated equilibrium brine slurry containing carnallite particles is preferably 30-70%, such as 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or a range consisting of any two values.

[0035] In order to further reduce the content of calcium impurities in carnallites concentrate, the method for preparing saturated balanced brine slurry containing carnallites particles preferably comprises: mixing carnallites precipitated from salt pans with saturated balanced brine, scrubbing them to pre-remove CaSO4, and then screening the particle size to obtain saturated balanced brine slurry containing carnallites particles. By mixing carnallites precipitated from salt pans with saturated balanced brine, scrubbing them to pre-remove CaSO4 and other impurities, large-sized carnallites can be crushed to further reduce the impurity content in carnallites concentrate, thereby further improving the quality of potassium chloride products.

[0036] In some embodiments, a screening device is used to screen the particle size, and the mixed slurry of carnallite particles with a particle size of ≤1 mm and balanced brine passes through the screening device for subsequent precipitation treatment. The large-size carnallite particles with a particle size of >1 mm after screening are returned for further scrubbing.

[0037] Specifically, a scrubbing machine is used for scrubbing treatment. In order to further improve the removal rate of impurities such as CaSO4, the preferred scrubbing treatment time is 10-20 minutes, such as 10 minutes, 12 minutes, 15 minutes, 18 minutes, 20 minutes or a range value composed of any two values.

[0038] In some embodiments, the Ca in the carnallite precipitated from the salt pan is 2+ The mass content of CaSO4 is 1.2-3.0%, and the mass content of CaSO4 is 4.0-7.0%. 2+ The mass content of is 1.2%, 1.5%, 1.8%, 2.0%, 2.2%, 2.5%, 2.8%, 3.0% or a range consisting of any two values; the mass content of CaSO4 is 4.0%, 4.2%, 4.5%, 4.8%, 5.0%, 5.2%, 5.5%, 5.8%, 6.0%, 6.2%, 6.5%, 6.8%, 7.0% or a range consisting of any two values.

[0039] In some embodiments, the saturated equilibrium brine contains MgCl and KCl, wherein the mass content of MgCl is 30-35%, and the mass content of KCl is 0.4-0.6%. Specifically, the mass content of MgCl is 30%, 31%, 32%, 33%, 33.47%, 34%, 35%, or a range consisting of any two values; the mass content of KCl is 0.4%, 0.42%, 0.45%, 0.48%, 0.5%, 0.52%, 0.55%, 0.58%, 0.6%, or a range consisting of any two values.

[0040] In this application, the precipitated Ca 2+ The precipitant is preferably one that can convert Ca 2+ Sulfate substances that precipitate without introducing new ions include, but are not limited to, any one or more of sodium sulfate or sodium bisulfate.

[0041] In order to further increase Ca 2+ The precipitation efficiency is preferably such that the molar concentration of the precipitant solution is 1-3 mol / L, such as 1 mol, 1.2 mol / L, 1.5 mol / L, 1.8 mol / L, 2.0 mol / L, 2.2 mol / L, 2.5 mol / L, 2.8 mol / L, 3.0 mol / L or a range consisting of any two values.

[0042] In order to further increase Ca 2+ The precipitation removal rate is preferably such that the mass ratio of the precipitant in the precipitant to the carnallite particles in the saturated equilibrium brine ore containing the carnallite particles is 1:20-1:10, such as 1:20, 1:18, 1:16, 1:15, 1:13, 1:10 or a range value consisting of any two values.

[0043] To further accelerate Ca 2+In order to improve the precipitation efficiency, it is preferred that the precipitant is added to the saturated equilibrium brine containing carnallite particles while stirring, the stirring speed is 80-100r / min, and the stirring time is 1-30min. Specifically, the stirring speed is 80r / min, 85r / min, 90r / min, 95r / min, 100r / min, or a range consisting of any two values; the stirring time is 1min, 2min, 5min, 8min, 10min, 15min, 20min, 25min, 30min, or a range consisting of any two values.

[0044] The NaCl collector used for NaCl capture is a commonly used collector in the art, such as alkyl morpholine. In particular, the use of dodecyl morpholine as the NaCl collector is more conducive to improving the NaCl capture rate.

[0045] In order to further improve the recovery rate of NaCl, the preferred dosage of NaCl is 80-120 g / t, such as 80 g / t, 85 g / t, 90 g / t, 95 g / t, 100 g / t, 105 g / t, 110 g / t, 120 g / t or a range consisting of any two values.

[0046] In a second typical embodiment of the present application, a process for producing potassium chloride by reverse flotation cold crystallization is also provided, and the process includes the method for removing calcium by reverse flotation of carnallite provided in the above-mentioned first typical embodiment.

[0047] The process for producing potassium chloride by reverse flotation cold crystallization provided in the present application adopts the carnallite concentrate prepared by the above-mentioned method for removing calcium by reverse flotation of carnallite as raw material, which not only does not clog the production equipment during the production process, but also can effectively improve the quality and yield of the potassium chloride product, and is also conducive to increasing production capacity and reducing production costs.

[0048] In some embodiments, the process for producing potassium chloride by reverse flotation cold crystallization includes: decomposing and crystallizing a carnallitite concentrate to obtain a potassium chloride product; wherein the carnallitite concentrate is a carnallitite concentrate obtained by the method for removing calcium by reverse flotation of carnallites provided in the first typical embodiment.

[0049] The present invention is to firstly use a precipitant to precipitate the balanced brine slurry containing carnallite particles to remove Ca 2+ Then, CaSO4 collector and NaCl collector are used to collect CaSO4 and NaCl for reverse flotation, which can greatly reduce the Ca contained in the carnallite precipitated from the salt field in the reverse flotation process. 2+and CaSO4 impurities, thereby obtaining low-calcium and low-sodium carnallite concentrate, which then enters the next decomposition and crystallization process to obtain high-quality and high-yield potassium chloride products. At the same time, it can also eliminate the blockage of production equipment caused by calcium impurities, maintain normal production, reduce maintenance costs, and increase production capacity.

[0050] The beneficial effects of the present application will be further illustrated below in combination with embodiments and comparative examples.

[0051] Example 1

[0052] This embodiment provides a method for removing calcium by reverse flotation of carnallite, which comprises the following steps:

[0053] (1) The carnallite (Ca 2+ The ore pulp of the present invention is mixed with saturated balanced brine (MgCl2 content is 33.47wt%, KCl content is 0.47wt%) to obtain a carnallite slurry with a concentration of 35wt%; the carnallite slurry is passed into a scrubbing machine for scrubbing treatment, and the scrubbing time is 10min. The scrubbed slurry enters a screening device, and the carnallite particles ≤1mm are passed into a slurry mixing tank, and the saturated balanced brine is used to adjust the slurry in the slurry mixing tank to obtain a saturated balanced brine slurry containing carnallite particles with a concentration of 35wt%.

[0054] (2) A sodium sulfate solution with a molar concentration of 1 mol / L was added to the saturated equilibrium brine slurry containing carnallite particles and stirred, and the mass ratio of sodium sulfate in the sodium sulfate solution to carnallite particles was 1:15, the stirring speed was 85 r / min, and the stirring time was 5 min, so that Ca 2+ After precipitation, it is discharged into the flotation tank and 100g / t CaSO4 collector and 100g / t NaCl collector are added. During the stirring process, aeration flotation is performed to obtain carnallite concentrate; wherein, the CaSO4 collector is composed of 60wt% alkyl ether amine and 40wt% modified fatty acid, and the NaCl collector is dodecyl morpholine; the alkyl ether amine is purchased from Kunming Liangfan Technology Co., Ltd., model LF-24, and the modified fatty acid is purchased from Guangzhou Zelong Chemical Technology Co., Ltd., model ZR-101.

[0055] Example 2

[0056] This embodiment provides a method for removing calcium by reverse flotation of carnallite, which comprises the following steps:

[0057] (1) The carnallite (Ca 2+The ore pulp of the present invention is mixed with saturated balanced brine (MgCl2 content is 33.47wt%, KCl content is 0.47wt%) to obtain a carnallite slurry with a concentration of 40wt%; the carnallite slurry is passed into a scrubbing machine for scrubbing treatment, and the scrubbing time is 15min. The scrubbed slurry enters a screening device, and the carnallite particles of ≤1mm are passed into a slurry mixing tank, and the saturated balanced brine is used to adjust the slurry in the slurry mixing tank to obtain a saturated balanced brine slurry containing carnallite particles with a concentration of 35wt%.

[0058] (2) A sodium sulfate solution with a molar concentration of 1.5 mol / L was added to the saturated equilibrium brine slurry containing carnallite particles and stirred, and the mass ratio of sodium sulfate in the sodium sulfate solution to carnallite particles was 1:15. The stirring speed was 85 r / min and the stirring time was 10 min. 2+ After precipitation, it is discharged into a flotation tank and 120g / t CaSO4 collector and 100g / t NaCl collector are added. During the stirring process, aeration flotation is performed to obtain a carnallite concentrate; wherein the CaSO4 collector is composed of 65wt% alkyl ether amine and 35wt% modified fatty acid, and the NaCl collector is dodecyl morpholine; the alkyl ether amine is purchased from Kunming Liangfan Technology Co., Ltd., model LF-24, and the modified fatty acid is purchased from Guangzhou Zelong Chemical Technology Co., Ltd., model ZR-101.

[0059] Example 3

[0060] This embodiment provides a method for removing calcium by reverse flotation of carnallite, which comprises the following steps:

[0061] (1) The carnallite (Ca 2+ The ore pulp of the present invention is mixed with saturated balanced brine (MgCl2 content is 33.47wt%, KCl content is 0.47wt%) to obtain a carnallite slurry with a concentration of 45wt%; the carnallite slurry is passed into a scrubbing machine for scrubbing treatment, and the scrubbing time is 15min. The scrubbed slurry enters a screening device, and the carnallite particles ≤1mm are passed into a slurry mixing tank, and the saturated balanced brine is used to adjust the slurry in the slurry mixing tank to obtain a saturated balanced brine slurry containing carnallite particles with a concentration of 40wt%.

[0062] (2) A sodium sulfate solution with a molar concentration of 1.5 mol / L was added to the saturated equilibrium brine slurry containing carnallite particles and stirred, and the mass ratio of sodium sulfate in the sodium sulfate solution to carnallite particles was 1:15. The stirring speed was 90 r / min and the stirring time was 15 min. 2+After precipitation, it is discharged into the flotation tank and 150g / t CaSO4 collector and 100g / t NaCl collector are added. During the stirring process, aeration flotation is performed to obtain carnallite concentrate; wherein, the CaSO4 collector is composed of 70wt% alkyl ether amine and 30wt% modified fatty acid, and the NaCl collector is dodecyl morpholine; the alkyl ether amine is purchased from Kunming Liangfan Technology Co., Ltd., model LF-24, and the modified fatty acid is purchased from Guangzhou Zelong Chemical Technology Co., Ltd., model ZR-101.

[0063] Example 4

[0064] This embodiment provides a method for removing calcium by reverse flotation of carnallite, which comprises the following steps:

[0065] (1) The carnallite (Ca 2+ The ore pulp of the present invention is mixed with saturated balanced brine (MgCl2 content is 33.47wt%, KCl content is 0.47wt%) to obtain a carnallite slurry with a concentration of 50wt%; the carnallite slurry is passed into a scrubbing machine for scrubbing treatment, and the scrubbing time is 15min. The scrubbed slurry enters a screening device, and the carnallite particles of ≤1mm are passed into a slurry mixing tank, and the saturated balanced brine is used to adjust the slurry in the slurry mixing tank to obtain a saturated balanced brine slurry containing carnallite particles with a concentration of 50wt%.

[0066] (2) A sodium sulfate solution with a molar concentration of 2 mol / L was added to the saturated equilibrium brine slurry containing carnallite particles and stirred, and the mass ratio of sodium sulfate in the sodium sulfate solution to carnallite particles was 1:15. The stirring speed was 90 r / min and the stirring time was 20 min, so that Ca 2+ After precipitation, it is discharged into the flotation tank and 200g / t CaSO4 collector and 100g / t NaCl collector are added. During the stirring process, aeration flotation is performed to obtain carnallite concentrate; wherein, the CaSO4 collector is composed of 75wt% alkyl ether amine and 25wt% modified fatty acid, and the NaCl collector is dodecyl morpholine; the alkyl ether amine is purchased from Kunming Liangfan Technology Co., Ltd., model LF-24, and the modified fatty acid is purchased from Guangzhou Zelong Chemical Technology Co., Ltd., model ZR-101.

[0067] Example 5

[0068] This embodiment provides a method for removing calcium by reverse flotation of carnallite, which comprises the following steps:

[0069] (1) The carnallite (Ca 2+The ore pulp of the present invention is mixed with saturated balanced brine (MgCl2 content is 33.47wt%, KCl content is 0.47wt%) to obtain a carnallite slurry with a concentration of 60wt%; the carnallite slurry is passed into a scrubbing machine for scrubbing treatment, and the scrubbing time is 20min. The scrubbed slurry enters a screening device, and the carnallite particles of ≤1mm are passed into a slurry mixing tank, and the saturated balanced brine is used to adjust the slurry in the slurry mixing tank to obtain a saturated balanced brine slurry containing carnallite particles with a concentration of 60wt%.

[0070] (2) A sodium sulfate solution with a molar concentration of 2.5 mol / L was added to the saturated equilibrium brine slurry containing carnallite particles and stirred, and the mass ratio of sodium sulfate in the sodium sulfate solution to carnallite particles was 1:15. The stirring speed was 100 r / min and the stirring time was 25 min. 2+ After precipitation, it is discharged into a flotation tank and 250g / t CaSO4 collector and 100g / t NaCl collector are added. During the stirring process, aeration flotation is performed to obtain a carnallite concentrate; wherein the CaSO4 collector is composed of 80wt% of alkyl ether amine and 20wt% of modified fatty acid, and the NaCl collector is dodecyl morpholine; the alkyl ether amine is purchased from Kunming Liangfan Technology Co., Ltd., model LF-24, and the modified fatty acid is purchased from Guangzhou Zelong Chemical Technology Co., Ltd., model ZR-101.

[0071] Example 6

[0072] This embodiment provides a method for removing calcium by reverse flotation of carnallite, which comprises the following steps:

[0073] (1) The carnallite (Ca 2+ The ore pulp of the present invention is mixed with saturated balanced brine (MgCl2 content is 33.47wt%, KCl content is 0.47wt%) to obtain a carnallite slurry with a concentration of 45wt%; the carnallite slurry is passed into a scrubbing machine for scrubbing treatment, and the scrubbing time is 15min. The scrubbed slurry enters a screening device, and the carnallite particles ≤1mm are passed into a slurry mixing tank, and the saturated balanced brine is used to adjust the slurry in the slurry mixing tank to obtain a saturated balanced brine slurry containing carnallite particles with a concentration of 35wt%.

[0074] (2) A sodium sulfate solution with a molar concentration of 1.5 mol / L was added to the saturated equilibrium brine slurry containing carnallite particles and stirred, and the mass ratio of sodium sulfate in the sodium sulfate solution to carnallite particles was 1:15, the stirring speed was 90 r / min, and the stirring time was 15 min, so that Ca 2+After precipitation, it is discharged into the flotation tank and 200g / t CaSO4 collector and 100g / t NaCl collector are added. During the stirring process, aeration flotation is performed to obtain carnallite concentrate; wherein, the CaSO4 collector is composed of 70wt% alkyl ether amine and 30wt% modified fatty acid, and the NaCl collector is dodecyl morpholine; the alkyl ether amine is purchased from Kunming Liangfan Technology Co., Ltd., model LF-24, and the modified fatty acid is purchased from Guangzhou Zelong Chemical Technology Co., Ltd., model ZR-101.

[0075] Example 7

[0076] The difference between this embodiment and embodiment 6 is that in step (1) and step (2), by adjusting the amount of saturated balanced brine, a saturated balanced brine slurry containing carnallite particles with a concentration of 70 wt% is prepared. Specifically, the following steps are included:

[0077] (1) The carnallite (Ca 2+ The ore pulp of the present invention is mixed with saturated balanced brine (MgCl2 content is 33.47wt%, KCl content is 0.47wt%) to obtain a carnallite slurry with a concentration of 70wt%; the carnallite slurry is passed into a scrubbing machine for scrubbing treatment, and the scrubbing time is 15min. The scrubbed slurry enters a screening device, and the carnallite particles of ≤1mm are passed into a slurry mixing tank, and the saturated balanced brine is used to adjust the slurry in the slurry mixing tank to obtain a saturated balanced brine slurry containing carnallite particles with a concentration of 70wt%.

[0078] (2) A sodium sulfate solution with a molar concentration of 1.5 mol / L is added to the saturated equilibrium brine slurry containing carnallites, and the mixture is stirred, wherein the mass ratio of sodium sulfate in the sodium sulfate solution to carnallites is 1:20, the stirring speed is 90 r / min, and the stirring time is 15 min, so that Ca2+ is precipitated. The mixture is then discharged into a flotation tank, 200 g / t of CaSO4 collector and 100 g / t of NaCl collector are added, and aeration flotation is performed during the stirring process to obtain a carnallites concentrate; wherein the CaSO4 collector is composed of 70 wt% of an alkyl ether amine and 70 wt% of a modified fatty acid, and the NaCl collector is dodecyl morpholine; the alkyl ether amine is purchased from Kunming Liangfan Technology Co., Ltd., and the model is LF-24; the modified fatty acid is purchased from Guangzhou Zelong Chemical Technology Co., Ltd., and the model is ZR-101.

[0079] Example 8

[0080] The difference between this embodiment and embodiment 6 is that in step (2), the mass ratio of sodium sulfate in the sodium sulfate solution to carnallite particles is 1:20.

[0081] Example 9

[0082] The difference between this embodiment and embodiment 6 is that in step (2), the mass ratio of sodium sulfate in the sodium sulfate solution to carnallite particles is 1:10.

[0083] Example 10

[0084] The difference between this embodiment and embodiment 6 is that in step (2), the amount of CaSO4 collector used is 300 g / t.

[0085] Embodiment 11

[0086] The difference between this embodiment and embodiment 6 is that in step (2), the mass ratio of sodium sulfate in the sodium sulfate solution to carnallite particles is 1:30.

[0087] Example 12

[0088] The difference between this embodiment and embodiment 6 is that in step (2), the mass ratio of sodium sulfate in the sodium sulfate solution to carnallite particles is 1:5.

[0089] Embodiment 13

[0090] The difference between this embodiment and embodiment 6 is that in step (1), after the carnallite precipitated from the salt field is crushed, the carnallite particles with a particle size of ≤1 mm are screened and mixed with saturated balanced brine to form a saturated balanced brine slurry containing carnallite particles with a concentration of 35wt%, without using a scrubbing machine for scrubbing.

[0091] Comparative Example 1

[0092] The difference between this comparative example and Example 6 is that the CaSO4 collector is composed of 50 wt% of alkyl ether amine and 50 wt% of modified fatty acid.

[0093] Comparative Example 2

[0094] The difference between this comparative example and Example 6 is that the CaSO4 collector is composed of 90 wt % of alkyl ether amine and 10 wt % of modified fatty acid.

[0095] Comparative Example 3

[0096] The difference between this comparative example and Example 6 is that the CaSO4 collector is an alkyl ether amine.

[0097] Comparative Example 4

[0098] The difference between this comparative example and Example 6 is that the CaSO4 collector is a modified fatty acid.

[0099] Test example

[0100] The carnallite concentrate prepared in the examples and comparative examples was subjected to Ca 2+ The mass content and CaSO4 mass content were tested, and the results are shown in Table 1 below.

[0101] The specific detection method is: (1) Ca 2+ Inductively coupled plasma optical emission spectrometry was used for detection;

[0102] (2) The mass content of CaSO4 is determined by a gravimetric method, specifically comprising: dissolving the obtained carnallite concentrate completely in water at 25°C and a humidity of 40%±5%, and then sieving it through a -325 mesh sieve. The weight of the insoluble matter on the sieve after drying is the weight of CaSO4, and the ratio of the weight of CaSO4 to the carnallite concentrate is the mass content of CaSO4.

[0103] Table 1

[0104] <![CDATA[Ca 2+ (%)]]> <![CDATA[CaSO4(%)]]> Example 1 0.65 2.93 Example 2 0.61 2.81 Example 3 0.53 2.62 Example 4 0.46 2.16 Example 5 0.50 2.34 Example 6 0.31 1.65 Example 7 0.64 2.31 Example 8 0.48 1.69 Example 9 0.28 1.71 Example 10 0.32 1.58 Embodiment 11 0.98 1.68 Example 12 0.33 1.63 Example 13 0.88 3.69 Comparative Example 1 0.48 3.97 Comparative Example 2 0.42 3.82 Comparative Example 3 0.55 4.09 Comparative Example 4 0.61 4.13

[0105] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: the method for removing calcium by reverse flotation of carnallite provided in the present application firstly adds a precipitant to a saturated equilibrium brine slurry containing carnallite particles to remove Ca 2+ It is removed from the brine, and then the NaCl and CaSO4 are captured and reverse floated by NaCl collectors and CaSO4 collectors to obtain carnallite concentrate. Therefore, the carnallite concentrate will not block the production equipment when used as a raw material to prepare potassium chloride products, and can effectively improve the quality and yield of potassium chloride products, and is also conducive to increasing production capacity and reducing production costs.

[0106] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for removing calcium by reverse flotation of carnallite, characterized in that: The method comprises: The Ca 2+ After precipitation, NaCl and CaSO4 are captured and reversely floated by NaCl collector and CaSO4 collector to obtain carnallite concentrate; Wherein, the CaSO4 collector comprises 60-80% alkyl ether amine and 20-40% modified fatty acid by mass percentage.

2. The method for removing calcium by reverse flotation of carnallite according to claim 1, characterized in that: The particle size of the carnallite particles in the saturated equilibrium brine slurry containing carnallite particles is ≤1 mm; Preferably, the mass concentration of the saturated equilibrium brine slurry containing carnallite particles is 30-70%.

3. The method for removing calcium by reverse flotation of carnallite according to claim 1, characterized in that: The preparation method of the saturated balanced brine slurry containing carnallite particles comprises: mixing the carnallite precipitated from the salt field with the saturated balanced brine, first scrubbing to remove CaSO4, and then screening the particle size to obtain the saturated balanced brine slurry containing the carnallite particles; Preferably, the scrubbing treatment is performed using a scrubbing machine, and the scrubbing treatment time is preferably 10-20 minutes.

4. The method for removing calcium by reverse flotation of carnallite according to claim 3, characterized in that: The Ca content of carnallite precipitated from the salt pan is 2+ The mass content of is 1.2-3.0%, and the mass content of CaSO4 is 4.0-7.0%.

5. The method for removing calcium by reverse flotation of carnallite according to claim 1, characterized in that: The precipitant in the precipitant solution includes at least one of sodium sulfate or sodium bisulfate; Preferably, the mass ratio of the precipitant in the precipitant solution to the carnallite particles in the saturated equilibrium brine slurry containing carnallite particles is 1:10-20; Preferably, the molar concentration of the precipitant solution is 1-3 mol / L.

6. The method for removing calcium by reverse flotation of carnallite according to claim 1, characterized in that: The precipitant is added while stirring, the stirring speed is 80-100 r / min, and the stirring time is 1-30 min.

7. The method for removing calcium by reverse flotation of carnallite according to claim 1, characterized in that: The NaCl collector comprises an alkyl morpholine, preferably dodecyl morpholine; Preferably, the dosage of the NaCl collector is 80-120 g / t.

8. The method for removing calcium by reverse flotation of carnallite according to any one of claims 1 to 7, characterized in that: The dosage of the CaSO4 collector is 100-300g / t; Preferably, the alkyl ether amine is purchased from Kunming Liangfan Technology Co., Ltd., model LF-24; Preferably, the modified fatty acid is purchased from Guangzhou Zelong Chemical Technology Co., Ltd., model number ZR-101.

9. A process for producing potassium chloride by reverse flotation cold crystallization, characterized in that: The process comprises the method for removing calcium by reverse flotation of carnallite according to any one of claims 1 to 8.

10. The process for producing potassium chloride by reverse flotation cold crystallization according to claim 9, characterized in that: The process comprises: The carnallites concentrate is decomposed and crystallized to obtain the potassium chloride product; wherein the carnallites concentrate is the carnallites concentrate obtained by the method for removing calcium by reverse flotation of carnallites according to any one of claims 1 to 8.