System for producing lithium carbonate and byproduct high-purity potassium sulfate by acidizing clinker through sulfuric acid method

Abstract

The utility model discloses a system for producing lithium carbonate and byproduct high-purity potassium sulfate by acidizing clinker through a sulfuric acid method, and solves the technical problems that the requirement of battery-grade lithium carbonate cannot be met and the lithium loss is large in the production process when the lithium carbonate is produced by acidizing clinker through the sulfuric acid method in the prior art. The system comprises a pulping system, a chemical impurity removal system connected out from the pulping system, a resin impurity removal device connected out from the chemical impurity removal system, an MVR evaporator connected out from the resin impurity removal device, an MVR freezing crystallizer connected out from the MVR evaporator, a lithium precipitation system connected out from the MVR freezing crystallizer, and a carbonization thermal analysis system connected out from the lithium precipitation system, the pulping system is connected with an acidified clinker conveying line, the MVR freezing crystallizer is connected with a high-purity potassium sulfate output line, and the carbonization and thermal analysis system is connected with a battery-grade lithium carbonate output line. The system disclosed by the utility model can effectively reduce lithium loss and produce battery-grade lithium carbonate, and meanwhile, a byproduct of high-purity potassium sulfate is also produced.

Description

Technical Field

[0001] The utility model belongs to the technical field of chemical industry, and specifically relates to a system for producing lithium carbonate by acidifying clinker with sulfuric acid method and producing high-purity potassium sulfate as a byproduct. Background Art

[0002] The use of sulfuric acid to extract lithium from lithium ore is widely used in the prior art. The principle is to use sulfuric acid to react with metal oxides in lithium ore to generate sulfates to obtain acidified clinker. After pulping and impurity removal, the acidified clinker is subjected to lithium precipitation, and the precipitate is refined to obtain lithium carbonate.

[0003] In the prior art, the slurry of acidified clinker after pulping is strongly acidic, and limestone is added to adjust the pH value to neutral (about 6.5-7) before pressing. This method will produce Al(OH) 3 Precipitation, Al(OH) 3 The precipitate is a colloidal substance and contains Al(OH) 3 Pressing and removing impurities from the raw materials will make it difficult to press and dehydrate, resulting in an increase in the moisture content of the leached residue, which will increase the loss of lithium in the leached residue. In the traditional process, the loss of lithium is mainly in the leached residue, about 18% to 25% of the total lithium is lost.

[0004] In addition, the purity requirement for battery-grade lithium carbonate is above 99.9%, and the impurity requirements include Na not more than 50ppm, K not more than 50ppm, Ca not more than 50ppm, Mg not more than 10ppm, Fe not more than 5ppm, Cu not more than 2ppm, Ni not more than 1ppm, and Zn not more than 0.1ppm.

[0005] The purity of lithium carbonate obtained by traditional acidified clinker pulping, impurity removal and lithium precipitation operations often cannot meet the requirements of battery-grade lithium carbonate, and the lithium loss is large.

[0006] Therefore, designing a system for producing lithium carbonate by acidifying clinker with sulfuric acid and producing high-purity potassium sulfate as a by-product, so that the produced lithium carbonate meets the requirements of battery-grade lithium carbonate and at the same time reduces lithium loss in the lithium carbonate production process, has become a technical problem that needs to be urgently solved by technicians in the relevant technical field. Utility Model Content

[0007] The technical problem to be solved by the utility model is: to provide a system for producing lithium carbonate by acidifying clinker with sulfuric acid method and producing high-purity potassium sulfate as a by-product, so as to solve the technical problem that the production of lithium carbonate by acidifying clinker with sulfuric acid method in the prior art cannot meet the requirements of battery-grade lithium carbonate and a large amount of lithium loss occurs during the production process.

[0008] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0009] A system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid method includes a pulping system, a chemical impurity removal system connected to the pulping system, a resin impurity removal device connected to the chemical impurity removal system, an MVR evaporator connected to the resin impurity removal device, an MVR freezing crystallizer connected to the MVR evaporator, a lithium precipitation system connected to the MVR freezing crystallizer, and a carbonization thermal analysis system connected to the lithium precipitation system; the pulping system is connected to the acidification clinker conveying line, the MVR freezing crystallizer is connected to the high-purity potassium sulfate external transmission line, and the carbonization thermal analysis system is connected to the battery-grade lithium carbonate external transmission line.

[0010] Furthermore, the pulping system includes a reactor connected to the acidified clinker conveying line, a press A connected to the reactor, and a high-precision membrane filter A connected to the liquid phase outlet of the press A; the clear liquid outlet of the high-precision membrane filter A is connected to the chemical impurity removal system, the concentrated liquid outlet of the high-precision membrane filter A is connected to the press A, and the reactor is connected to a pulping water conveying pipeline.

[0011] Furthermore, the solid phase outlet of press A is connected to a leached residue stirring and washing tank, the leached residue stirring and washing tank is connected to a process water delivery pipeline A, the leached residue stirring and washing tank is connected to press B, the liquid phase outlet of press B is connected to the reactor, and the solid phase outlet of press B is connected to a leached residue external transmission line.

[0012] Furthermore, the chemical impurity removal system includes a pH adjusting tank A connected to the pulping system, a first-level press connected to the pH adjusting tank A, a first-level high-precision membrane filter connected to the liquid phase outlet of the first-level press, a pH adjusting tank B connected to the clear liquid outlet of the first-level high-precision membrane filter, a second-level press connected to the pH adjusting tank B, a second-level high-precision membrane filter connected to the liquid phase outlet of the second-level press, and a clear liquid storage tank connected to the clear liquid outlet of the second-level high-precision membrane filter and connected to the resin impurity removal device.

[0013] Furthermore, the chemical impurity removal system also includes an impurity removal slag stirring and washing tank connected to the solid phase outlet of the first press and the solid phase outlet of the second press respectively, and a press C connected to the impurity removal slag stirring and washing tank.

[0014] Furthermore, the liquid phase outlet of the press C is connected to the pulping system, the solid phase outlet of the press C is connected to a debris removal transmission line, and the debris removal stirring and washing tank is connected to a process water transmission pipeline B.

[0015] Furthermore, the pH adjusting tank A is connected to a first alkali material conveying line, and the pH adjusting tank B is connected to a second alkali material conveying line.

[0016] Furthermore, the concentrate outlet of the first-stage high-precision membrane filter is connected to a first-stage press.

[0017] Furthermore, the concentrated liquid phase outlet of the secondary high-precision membrane filter is connected to a secondary press.

[0018] Furthermore, it also includes a purified liquid storage tank which is connected from the resin impurity removal device and connected to the MVR evaporator.

[0019] Compared with the prior art, the utility model has the following beneficial effects:

[0020] The utility model is scientifically and rationally designed. The acidic extract is directly squeezed under acidic conditions after slurry adjustment without adjusting pH. The leaching residue does not contain Al(OH) 3 The colloid-like substance can efficiently separate solids from liquids, minimize the water content of the leached residue, and reduce the amount of leached residue discharged. Since the leached residue has the largest amount of slag discharged in and out of the system, reducing the amount of leached residue can greatly reduce the loss of lithium. The loss of lithium in the leached residue accounts for about 2.5% to 5% of the total lithium, which is more than half lower than the traditional process, greatly improving the comprehensive utilization rate of lithium.

[0021] The utility model system can effectively reduce lithium loss and produce battery-grade lithium carbonate, while also producing high-purity potassium sulfate as a by-product. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a system diagram of the utility model.

[0023] Figure 2 This is another system diagram of the utility model.

[0024] The names corresponding to the reference numerals are:

[0025] 1- pulping system, 2- chemical impurity removal system, 3- resin impurity removal device, 4- MVR evaporator, 5- MVR freezing crystallizer, 6- lithium precipitation system, 7- carbonization thermal analysis system, 8- acidification clinker transmission line, 9- high purity potassium sulfate transmission line, 10- battery grade lithium carbonate transmission line, 11- reactor, 12- press A, 13- high precision membrane filter A, 14- pulping water transmission line, 15- leached slag stirring and washing tank, 16- process water transmission pipeline A, 17- Press B, 18-leached residue external transmission line, 19-PH adjusting tank A, 20-first alkali material transmission line, 21-first-level press, 22-first-level high-precision membrane filter, 23-PH adjusting tank B, 24-second alkali material transmission line, 25-second-level press, 26-second-level high-precision membrane filter, 27-clear liquid storage tank, 28-residue removal stirring and washing tank, 29-press C, 30-residue removal external transmission line, 31-process water transmission pipeline B, 32-purified liquid storage tank. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0027] Example 1.

[0028] like Figure 1 and Figure 2 As shown, the utility model provides a system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid method, comprising a pulping system 1, a chemical impurity removal system 2 connected to the pulping system 1, a resin impurity removal device 3 connected to the chemical impurity removal system 2, an MVR evaporator 4 connected to the resin impurity removal device 3, an MVR freezing crystallizer 5 connected to the MVR evaporator 4, a lithium precipitation system 6 connected to the MVR freezing crystallizer 5, and a carbonization pyrolysis system 7 connected to the lithium precipitation system 6; the pulping system 1 is connected to an acidified clinker conveying line 8, the MVR freezing crystallizer 5 is connected to a high-purity potassium sulfate external transmission line 9, and the carbonization pyrolysis system 7 is connected to a battery-grade lithium carbonate external transmission line 10.

[0029] The utility model system can effectively reduce lithium loss and produce battery-grade lithium carbonate, while also producing high-purity potassium sulfate as a by-product.

[0030] Example 2.

[0031] like Figure 1 and Figure 2 As shown, the utility model provides a system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid method, comprising a pulping system 1, a chemical impurity removal system 2 connected to the pulping system 1, a resin impurity removal device 3 connected to the chemical impurity removal system 2, an MVR evaporator 4 connected to the resin impurity removal device 3, an MVR freezing crystallizer 5 connected to the MVR evaporator 4, a lithium precipitation system 6 connected to the MVR freezing crystallizer 5, and a carbonization pyrolysis system 7 connected to the lithium precipitation system 6; the pulping system 1 is connected to an acidified clinker conveying line 8, the MVR freezing crystallizer 5 is connected to a high-purity potassium sulfate external transmission line 9, and the carbonization pyrolysis system 7 is connected to a battery-grade lithium carbonate external transmission line 10.

[0032] The pulping system 1 includes a reactor 11 connected to the acidified clinker conveying line 8, a press A12 connected to the reactor 11, and a high-precision membrane filter A13 connected to the liquid phase outlet of the press A12; the clear liquid outlet of the high-precision membrane filter A13 is connected to the chemical impurity removal system 2, the concentrated liquid outlet of the high-precision membrane filter A13 is connected to the press A12, and the reactor 11 is connected to the pulping water conveying pipeline 14.

[0033] The high-precision membrane filter in this embodiment is a YT membrane filter.

[0034] Based on Example 1, this Example 2 provides a more preferred structure of the pulping system 1, specifically: the pulping system 1 includes a reactor 11 connected to the acidified clinker conveying line 8, a press A12 connected to the reactor 11, and a high-precision membrane filter A13 connected to the liquid phase outlet of the press A12; the clear liquid outlet of the high-precision membrane filter A13 is connected to the chemical impurity removal system 2, the concentrated liquid outlet of the high-precision membrane filter A13 is connected to the press A12, and the reactor 11 is connected to the pulping water conveying pipeline 14. The design of the utility model is scientific and reasonable, and the acidic extract is directly squeezed under acidic conditions after pulping without adjusting the pH. Leaching and squeezing under acidic conditions, the leached residue does not contain Al(OH) 3 The colloid-like substance can efficiently separate solids from liquids, minimize the water content of the leached residue, and reduce the amount of leached residue discharged. Since the leached residue has the largest amount of slag discharged in and out of the system, reducing the amount of leached residue can greatly reduce the loss of lithium. The loss of lithium in the leached residue accounts for about 2.5% to 5% of the total lithium, which is more than half lower than the traditional process, greatly improving the comprehensive utilization rate of lithium.

[0035] Example 3.

[0036] like Figure 1 and Figure 2 As shown, the utility model provides a system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid method, comprising a pulping system 1, a chemical impurity removal system 2 connected to the pulping system 1, a resin impurity removal device 3 connected to the chemical impurity removal system 2, an MVR evaporator 4 connected to the resin impurity removal device 3, an MVR freezing crystallizer 5 connected to the MVR evaporator 4, a lithium precipitation system 6 connected to the MVR freezing crystallizer 5, and a carbonization pyrolysis system 7 connected to the lithium precipitation system 6; the pulping system 1 is connected to an acidified clinker conveying line 8, the MVR freezing crystallizer 5 is connected to a high-purity potassium sulfate external transmission line 9, and the carbonization pyrolysis system 7 is connected to a battery-grade lithium carbonate external transmission line 10.

[0037] The pulping system 1 includes a reactor 11 connected to the acidified clinker conveying line 8, a press A12 connected to the reactor 11, and a high-precision membrane filter A13 connected to the liquid phase outlet of the press A12; the clear liquid outlet of the high-precision membrane filter A13 is connected to the chemical impurity removal system 2, the concentrated liquid outlet of the high-precision membrane filter A13 is connected to the press A12, and the reactor 11 is connected to the pulping water conveying pipeline 14.

[0038] The solid phase outlet of the press A12 is connected to the leached residue stirring and washing tank 15, the leached residue stirring and washing tank 15 is connected to the process water delivery pipeline A16, the leached residue stirring and washing tank 15 is connected to the press B17, the liquid phase outlet of the press B17 is connected to the reactor 11, and the solid phase outlet of the press B17 is connected to the leached residue external delivery line 18. The high-precision membrane filter in this embodiment is a YT membrane filter.

[0039] Based on Example 2, this Example 3 provides a more preferred structure of the squeezer A12, specifically: the solid phase outlet of the squeezer A12 is connected to the leached residue stirring and washing tank 15, the leached residue stirring and washing tank 15 is connected to the process water delivery pipeline A16, the leached residue stirring and washing tank 15 is connected to the squeezer B17, the liquid phase outlet of the squeezer B17 is connected to the reactor 11, and the solid phase outlet of the squeezer B17 is connected to the leached residue external delivery line 18. The design of the utility model is scientific and reasonable, and the acidic extract is directly squeezed under acidic conditions after slurrying, without adjusting the pH. Leaching and squeezing under acidic conditions, the leached residue does not contain Al(OH) 3 The colloid-like substance can efficiently separate solids from liquids, minimize the water content of the leached residue, and reduce the amount of leached residue discharged. Since the leached residue has the largest amount of slag discharged in and out of the system, reducing the amount of leached residue can greatly reduce the loss of lithium. The loss of lithium in the leached residue accounts for about 2.5% to 5% of the total lithium, which is more than half lower than the traditional process, greatly improving the comprehensive utilization rate of lithium.

[0040] Example 4.

[0041] like Figure 1 and Figure 2 As shown, the utility model provides a system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid method, comprising a pulping system 1, a chemical impurity removal system 2 connected to the pulping system 1, a resin impurity removal device 3 connected to the chemical impurity removal system 2, an MVR evaporator 4 connected to the resin impurity removal device 3, an MVR freezing crystallizer 5 connected to the MVR evaporator 4, a lithium precipitation system 6 connected to the MVR freezing crystallizer 5, and a carbonization pyrolysis system 7 connected to the lithium precipitation system 6; the pulping system 1 is connected to an acidified clinker conveying line 8, the MVR freezing crystallizer 5 is connected to a high-purity potassium sulfate external transmission line 9, and the carbonization pyrolysis system 7 is connected to a battery-grade lithium carbonate external transmission line 10.

[0042] The chemical impurity removal system 2 includes a pH adjustment tank A19 connected to the pulping system 1, a primary press 21 connected to the pH adjustment tank A19, a primary high-precision membrane filter 22 connected to the liquid phase outlet of the primary press 21, a pH adjustment tank B23 connected to the clear liquid outlet of the primary high-precision membrane filter 22, a secondary press 25 connected to the pH adjustment tank B23, a secondary high-precision membrane filter 26 connected to the liquid phase outlet of the secondary press 25, and a clear liquid storage tank 27 connected to the clear liquid outlet of the secondary high-precision membrane filter 26 and connected to the resin impurity removal device 3. The high-precision membrane filter in this embodiment is a YT membrane filter.

[0043] Based on Example 1, this Example 4 provides a more preferred structure of the chemical impurity removal system 2, specifically: the chemical impurity removal system 2 includes a PH adjusting tank A19 connected to the pulping system 1, a first-level press 21 connected to the PH adjusting tank A19, a first-level high-precision membrane filter 22 connected to the liquid phase outlet of the first-level press 21, a PH adjusting tank B23 connected to the clear liquid outlet of the first-level high-precision membrane filter 22, a second-level press 25 connected to the PH adjusting tank B23, a second-level high-precision membrane filter 26 connected to the liquid phase outlet of the second-level press 25, and a clear liquid storage tank 27 connected to the clear liquid outlet of the second-level high-precision membrane filter 26 and connected to the resin impurity removal device 3.

[0044] The utility model system uses KOH as a decontamination agent for chemical decontamination, which is different from the traditional method of using lime milk Ca(OH) 2 The impurity removal produces a small amount of slag, with low processing costs, and can also produce high-purity potassium sulfate as a by-product. Compared with the use of sodium hydroxide for chemical impurity removal, it does not produce a large amount of lithium-containing complex salts, effectively reducing lithium losses.

[0045] Example 5.

[0046] like Figure 1 and Figure 2 As shown, the utility model provides a system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid method, comprising a pulping system 1, a chemical impurity removal system 2 connected to the pulping system 1, a resin impurity removal device 3 connected to the chemical impurity removal system 2, an MVR evaporator 4 connected to the resin impurity removal device 3, an MVR freezing crystallizer 5 connected to the MVR evaporator 4, a lithium precipitation system 6 connected to the MVR freezing crystallizer 5, and a carbonization pyrolysis system 7 connected to the lithium precipitation system 6; the pulping system 1 is connected to an acidified clinker conveying line 8, the MVR freezing crystallizer 5 is connected to a high-purity potassium sulfate external transmission line 9, and the carbonization pyrolysis system 7 is connected to a battery-grade lithium carbonate external transmission line 10.

[0047] The chemical impurity removal system 2 includes a pH adjusting tank A19 connected to the pulping system 1, a first-level press 21 connected to the pH adjusting tank A19, a first-level high-precision membrane filter 22 connected to the liquid phase outlet of the first-level press 21, a pH adjusting tank B23 connected to the clear liquid outlet of the first-level high-precision membrane filter 22, a second-level press 25 connected to the pH adjusting tank B23, a second-level high-precision membrane filter 26 connected to the liquid phase outlet of the second-level press 25, and a clear liquid storage tank 27 connected to the clear liquid outlet of the second-level high-precision membrane filter 26 and connected to the resin impurity removal device 3.

[0048] The chemical impurity removal system 2 further includes an impurity removal slag stirring and washing tank 28 connected to the solid phase outlet of the first press 21 and the solid phase outlet of the second press 25 respectively, and a press C29 connected to the impurity removal slag stirring and washing tank 28.

[0049] The high-precision membrane filter in this embodiment is a YT membrane filter.

[0050] Based on Example 4, this Example 5 provides a more preferred structure of the chemical impurity removal system 2, specifically: the chemical impurity removal system 2 also includes a slag stirring and washing tank 28 connected to the solid phase outlet of the first press 21 and the solid phase outlet of the second press 25, and a press C29 connected to the slag stirring and washing tank 28. In this way, lithium in the impurity removal slag can be effectively recovered, further reducing lithium loss. The system of the utility model uses KOH as an impurity removal agent for chemical impurity removal, which is different from the traditional method of using lime milk Ca(OH) 2 The impurity removal produces a small amount of slag, with low processing costs, and can also produce high-purity potassium sulfate as a by-product. Compared with the use of sodium hydroxide for chemical impurity removal, it does not produce a large amount of lithium-containing complex salts, effectively reducing lithium losses.

[0051] Example 6.

[0052] like Figure 1 and Figure 2 As shown, the utility model provides a system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid method, comprising a pulping system 1, a chemical impurity removal system 2 connected to the pulping system 1, a resin impurity removal device 3 connected to the chemical impurity removal system 2, an MVR evaporator 4 connected to the resin impurity removal device 3, an MVR freezing crystallizer 5 connected to the MVR evaporator 4, a lithium precipitation system 6 connected to the MVR freezing crystallizer 5, and a carbonization pyrolysis system 7 connected to the lithium precipitation system 6; the pulping system 1 is connected to an acidified clinker conveying line 8, the MVR freezing crystallizer 5 is connected to a high-purity potassium sulfate external transmission line 9, and the carbonization pyrolysis system 7 is connected to a battery-grade lithium carbonate external transmission line 10.

[0053] The chemical impurity removal system 2 includes a pH adjusting tank A19 connected to the pulping system 1, a first-level press 21 connected to the pH adjusting tank A19, a first-level high-precision membrane filter 22 connected to the liquid phase outlet of the first-level press 21, a pH adjusting tank B23 connected to the clear liquid outlet of the first-level high-precision membrane filter 22, a second-level press 25 connected to the pH adjusting tank B23, a second-level high-precision membrane filter 26 connected to the liquid phase outlet of the second-level press 25, and a clear liquid storage tank 27 connected to the clear liquid outlet of the second-level high-precision membrane filter 26 and connected to the resin impurity removal device 3.

[0054] The chemical impurity removal system 2 further includes an impurity removal slag stirring and washing tank 28 connected to the solid phase outlet of the first press 21 and the solid phase outlet of the second press 25 respectively, and a press C29 connected to the impurity removal slag stirring and washing tank 28.

[0055] The liquid phase outlet of the press C29 is connected to the pulping system 1, the solid phase outlet of the press C29 is connected to the debris removal external transmission line 30, and the debris removal stirring and washing tank 28 is connected to the process water transmission pipeline B31.

[0056] The high-precision membrane filter in this embodiment is a YT membrane filter.

[0057] Based on Example 5, this Example 6 provides a more preferred structure of the chemical impurity removal system 2, specifically: the liquid phase outlet of the squeezer C29 is connected to the pulping system 1, the solid phase outlet of the squeezer C29 is connected to the impurity removal slag external transmission line 30, and the impurity removal slag stirring and washing tank 28 is connected to the process water transmission pipeline B31. The liquid phase outlet of the squeezer C (29) is specifically connected to the reactor (11) in the pulping system 1. In this way, the lithium in the impurity removal slag can be effectively recovered, further reducing lithium loss. The system of the utility model uses KOH as an impurity removal agent for chemical impurity removal. Compared with the traditional method of using lime milk Ca(OH) 2 The impurity removal produces a small amount of slag, with low processing costs, and can also produce high-purity potassium sulfate as a by-product. Compared with the use of sodium hydroxide for chemical impurity removal, it does not produce a large amount of lithium-containing complex salts, effectively reducing lithium losses.

[0058] Example 7.

[0059] like Figure 1 and Figure 2As shown, the utility model provides a system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid method, comprising a pulping system 1, a chemical impurity removal system 2 connected to the pulping system 1, a resin impurity removal device 3 connected to the chemical impurity removal system 2, an MVR evaporator 4 connected to the resin impurity removal device 3, an MVR freezing crystallizer 5 connected to the MVR evaporator 4, a lithium precipitation system 6 connected to the MVR freezing crystallizer 5, and a carbonization pyrolysis system 7 connected to the lithium precipitation system 6; the pulping system 1 is connected to an acidified clinker conveying line 8, the MVR freezing crystallizer 5 is connected to a high-purity potassium sulfate external transmission line 9, and the carbonization pyrolysis system 7 is connected to a battery-grade lithium carbonate external transmission line 10.

[0060] The chemical impurity removal system 2 includes a pH adjusting tank A19 connected to the pulping system 1, a first-level press 21 connected to the pH adjusting tank A19, a first-level high-precision membrane filter 22 connected to the liquid phase outlet of the first-level press 21, a pH adjusting tank B23 connected to the clear liquid outlet of the first-level high-precision membrane filter 22, a second-level press 25 connected to the pH adjusting tank B23, a second-level high-precision membrane filter 26 connected to the liquid phase outlet of the second-level press 25, and a clear liquid storage tank 27 connected to the clear liquid outlet of the second-level high-precision membrane filter 26 and connected to the resin impurity removal device 3.

[0061] The PH adjusting tank A19 is connected to a first alkali material conveying line 20, and the PH adjusting tank B23 is connected to a second alkali material conveying line 24, which are used to input alkali solution for adjusting the pH value into the PH adjusting tank A19 and the PH adjusting tank B23 respectively.

[0062] The high-precision membrane filter in this embodiment is a YT membrane filter.

[0063] Based on Example 4, Example 7 provides a more preferred structure of the chemical impurity removal system 2, specifically: the PH adjustment tank 19 is connected to the first alkali material conveying line 20, and the PH adjustment tank B23 is connected to the second alkali material conveying line 24. The system of the utility model uses KOH as an impurity remover for chemical impurity removal, which is different from the traditional method of using lime milk Ca(OH) 2 The impurity removal produces a small amount of slag, with low processing costs, and can also produce high-purity potassium sulfate as a by-product. Compared with the use of sodium hydroxide for chemical impurity removal, it does not produce a large amount of lithium-containing complex salts, effectively reducing lithium losses.

[0064] Example 8.

[0065] like Figure 1 and Figure 2As shown, the utility model provides a system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid method, comprising a pulping system 1, a chemical impurity removal system 2 connected to the pulping system 1, a resin impurity removal device 3 connected to the chemical impurity removal system 2, an MVR evaporator 4 connected to the resin impurity removal device 3, an MVR freezing crystallizer 5 connected to the MVR evaporator 4, a lithium precipitation system 6 connected to the MVR freezing crystallizer 5, and a carbonization pyrolysis system 7 connected to the lithium precipitation system 6; the pulping system 1 is connected to an acidified clinker conveying line 8, the MVR freezing crystallizer 5 is connected to a high-purity potassium sulfate external transmission line 9, and the carbonization pyrolysis system 7 is connected to a battery-grade lithium carbonate external transmission line 10.

[0066] The chemical impurity removal system 2 includes a pH adjusting tank A19 connected to the pulping system 1, a first-level press 21 connected to the pH adjusting tank A19, a first-level high-precision membrane filter 22 connected to the liquid phase outlet of the first-level press 21, a pH adjusting tank B23 connected to the clear liquid outlet of the first-level high-precision membrane filter 22, a second-level press 25 connected to the pH adjusting tank B23, a second-level high-precision membrane filter 26 connected to the liquid phase outlet of the second-level press 25, and a clear liquid storage tank 27 connected to the clear liquid outlet of the second-level high-precision membrane filter 26 and connected to the resin impurity removal device 3.

[0067] The concentrate outlet of the primary high-precision membrane filter 22 is connected to the primary press 21 .

[0068] The high-precision membrane filter in this embodiment is a YT membrane filter.

[0069] Based on Example 4, this Example 8 provides a more preferred structure of the chemical impurity removal system 2, specifically: the concentrate outlet of the first-level high-precision membrane filter 22 is connected to the first-level press 21. The concentrate of the first-level high-precision membrane filter 22 is circulated and squeezed, which can effectively reduce lithium loss.

[0070] Example 9.

[0071] like Figure 1 and Figure 2 As shown, the utility model provides a system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid method, comprising a pulping system 1, a chemical impurity removal system 2 connected to the pulping system 1, a resin impurity removal device 3 connected to the chemical impurity removal system 2, an MVR evaporator 4 connected to the resin impurity removal device 3, an MVR freezing crystallizer 5 connected to the MVR evaporator 4, a lithium precipitation system 6 connected to the MVR freezing crystallizer 5, and a carbonization pyrolysis system 7 connected to the lithium precipitation system 6; the pulping system 1 is connected to an acidified clinker conveying line 8, the MVR freezing crystallizer 5 is connected to a high-purity potassium sulfate external transmission line 9, and the carbonization pyrolysis system 7 is connected to a battery-grade lithium carbonate external transmission line 10.

[0072] The chemical impurity removal system 2 includes a pH adjusting tank A19 connected to the pulping system 1, a first-level press 21 connected to the pH adjusting tank A19, a first-level high-precision membrane filter 22 connected to the liquid phase outlet of the first-level press 21, a pH adjusting tank B23 connected to the clear liquid outlet of the first-level high-precision membrane filter 22, a second-level press 25 connected to the pH adjusting tank B23, a second-level high-precision membrane filter 26 connected to the liquid phase outlet of the second-level press 25, and a clear liquid storage tank 27 connected to the clear liquid outlet of the second-level high-precision membrane filter 26 and connected to the resin impurity removal device 3.

[0073] The concentrate outlet of the secondary high-precision membrane filter 26 is connected to the secondary press 25 .

[0074] The high-precision membrane filter in this embodiment is a YT membrane filter.

[0075] Based on Example 4, this Example 9 provides a more preferred structure of the chemical impurity removal system 2, specifically: the concentrate outlet of the secondary high-precision membrane filter 26 is connected to the secondary press 25. The concentrated solution of the secondary high-precision membrane filter 26 is circulated and squeezed, which can effectively reduce lithium loss.

[0076] Example 10.

[0077] like Figure 1 and Figure 2 As shown, the utility model provides a system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid method, comprising a pulping system 1, a chemical impurity removal system 2 connected to the pulping system 1, a resin impurity removal device 3 connected to the chemical impurity removal system 2, an MVR evaporator 4 connected to the resin impurity removal device 3, an MVR freezing crystallizer 5 connected to the MVR evaporator 4, a lithium precipitation system 6 connected to the MVR freezing crystallizer 5, and a carbonization pyrolysis system 7 connected to the lithium precipitation system 6; the pulping system 1 is connected to an acidified clinker conveying line 8, the MVR freezing crystallizer 5 is connected to a high-purity potassium sulfate external transmission line 9, and the carbonization pyrolysis system 7 is connected to a battery-grade lithium carbonate external transmission line 10.

[0078] It also includes a purified liquid storage tank 32 which is connected from the resin impurity removal device 3 and connected to the MVR evaporator 4 .

[0079] Based on Example 1, this Example 10 provides a more preferred structure of the system, specifically: it also includes a purified liquid storage tank 32 connected from the resin impurity removal device 3 and connected to the MVR evaporator 4. The purified liquid storage tank 32 acts as a buffer to ensure that the purified liquid is continuously and stably supplied to the lithium precipitation system 6.

[0080] The lithium precipitation system 6 and carbonization thermal analysis system 7 used in the present invention are existing known lithium precipitation systems and carbonization thermal analysis systems, and are both mature production systems in the lithium carbonate preparation industry. Therefore, the specific working principles and equipment structures of the lithium precipitation system 6 and the carbonization thermal analysis system 7 are not described in detail here.

[0081] The utility model is matched with a matching production process of producing battery-grade lithium carbonate by acidifying clinker with sulfuric acid method and producing high-purity potassium sulfate as a by-product, and the production process comprises the following steps:

[0082] Step 1. Slurry preparation and pressing: The acidified clinker is slurried with slurry preparation water, and then the slurry is pressed to remove impurities, and the leaching liquid and leaching residue are obtained respectively. The leaching liquid is filtered through a high-precision membrane, and the clear liquid enters step 2 for chemical impurity removal; the concentrated liquid returns, is mixed with the slurry and then pressed again; the leaching residue obtained by pressing in step 1 is washed with water, and then pressed, and the resulting liquid phase returns to step 1 for slurry preparation.

[0083] Step 2. Chemical impurity removal: Add potassium hydroxide to the clear liquid after high-precision membrane filtration in step 1 to adjust the pH to neutral to precipitate impurities; squeeze and remove impurities from the mixed solution that generates the precipitate to obtain a liquid phase and a solid-liquid phase, respectively. The step 2 includes the steps of primary chemical impurity removal, primary pressing, primary filtration, secondary chemical impurity removal, secondary pressing, and secondary filtration in sequence; firstly, potassium hydroxide is added to the clear liquid after high-precision membrane filtration to adjust the pH to neutral to precipitate impurities, and then the first-level pressing impurity removal is carried out to obtain a first-level pressing impurity removal liquid phase and a first-level pressing impurity removal solid phase respectively; the first-level pressing impurity removal liquid phase is filtered through a high-precision membrane to obtain a first-level clear liquid and a first-level concentrated liquid; potassium hydroxide is added to the first-level clear liquid to adjust the pH value to alkaline to precipitate impurities, and then the second-level pressing impurity removal is carried out to obtain a second-level pressing impurity removal liquid phase and a second-level pressing impurity removal solid phase respectively; the second-level pressing impurity removal liquid phase is filtered through a high-precision membrane to obtain a second-level clear liquid and a second-level concentrated liquid, and the second-level clear liquid enters step 3; the first-level concentrated liquid is returned and the first-level pressing impurity removal is carried out again; the second-level concentrated liquid is returned and the second-level pressing impurity removal is carried out again. After the first-level pressing impurity removal solid phase and the second-level pressing impurity removal solid phase are combined, water is added to stir and wash, and after being pressed by a press, the resulting liquid phase is returned to step 1 as slurry water for slurry adjustment.

[0084] Step 3. Deep impurity removal with resin: The liquid phase after the impurity removal in step 2 is passed into an ion exchange resin system for deep impurity removal to obtain a purified mother liquor, wherein the resin is a chelating resin for removing calcium and magnesium.

[0085] Step 4. Concentration and impurity removal: The mother liquor is evaporated and concentrated to remove impurities; so that the impurities As, Be and Tl are precipitated and removed.

[0086] Step 5. Separation of potassium sulfate: Freeze the concentrated and impurity-free mother liquor to -10 to 0°C, crystallize, and separate potassium sulfate.

[0087] Step 6. Lithium precipitation: Add sodium carbonate to the mother liquor after separation of potassium sulfate, increase the temperature, and precipitate lithium.

[0088] Add excess sodium carbonate to the mother liquor after potassium sulfate separation; the amount of sodium carbonate added is 5-10% excess according to the lithium concentration; raise the temperature to ≥80°C to precipitate lithium. After lithium precipitation, separate the lithium carbonate precipitate and the lithium precipitation mother liquor, and the lithium carbonate precipitate enters the refining step; the lithium precipitation mother liquor undergoes secondary lithium precipitation. The lithium carbonate precipitate is stirred, washed, carbonized, thermally analyzed, and dried to obtain battery-grade lithium carbonate.

[0089] Finally, it should be noted that the above embodiments are only preferred embodiments of the utility model to illustrate the technical solution of the utility model, but not to limit it, and certainly not to limit the patent scope of the utility model. Any changes or modifications that have no substantial significance on the main design concept and spirit of the utility model, which solve technical problems consistent with the utility model, should be included in the protection scope of the utility model; in addition, the direct or indirect application of the technical solution of the utility model in other related technical fields should also be included in the patent protection scope of the utility model.

Claims

1. Sulfuric acid method to acidify clinker to produce lithium carbonate and produce high-purity potassium sulfate as a by-product system, It is characterized in that The invention comprises a pulping system (1), a chemical impurity removal system (2) connected to the pulping system (1), a resin impurity removal device (3) connected to the chemical impurity removal system (2), an MVR evaporator (4) connected to the resin impurity removal device (3), an MVR freezing crystallizer (5) connected to the MVR evaporator (4), a lithium precipitation system (6) connected to the MVR freezing crystallizer (5), and a carbonization pyrolysis system (7) connected to the lithium precipitation system (6); the pulping system (1) is connected to an acidified clinker conveying line (8), the MVR freezing crystallizer (5) is connected to a high-purity potassium sulfate transmission line (9), and the carbonization pyrolysis system (7) is connected to a battery-grade lithium carbonate transmission line (10).

2. The system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid process according to claim 1, It is characterized in that The pulping system (1) comprises a reactor (11) connected to an acidified clinker conveying line (8), a press A (12) connected to the reactor (11), and a high-precision membrane filter A (13) connected to a liquid phase outlet of the press A (12); the clear liquid outlet of the high-precision membrane filter A (13) is connected to a chemical impurity removal system (2), the concentrated liquid outlet of the high-precision membrane filter A (13) is connected to the press A (12), and the reactor (11) is connected to a pulping water conveying pipeline (14).

3. The system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid process according to claim 2, It is characterized in that The solid phase outlet of the press A (12) is connected to a leached residue stirring and washing tank (15), the leached residue stirring and washing tank (15) is connected to a process water delivery pipeline A (16), the leached residue stirring and washing tank (15) is connected to a press B (17), the liquid phase outlet of the press B (17) is connected to the reaction kettle (11), and the solid phase outlet of the press B (17) is connected to a leached residue delivery line (18).

4. The system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid process according to claim 1, It is characterized in that The chemical impurity removal system (2) comprises a pH regulating tank A (19) connected to the pulping system (1), a primary press (21) connected to the pH regulating tank A (19), a primary high-precision membrane filter (22) connected to the liquid phase outlet of the primary press (21), a pH regulating tank B (23) connected to the clear liquid outlet of the primary high-precision membrane filter (22), a secondary press (25) connected to the pH regulating tank B (23), a secondary high-precision membrane filter (26) connected to the liquid phase outlet of the secondary press (25), and a clear liquid storage tank (27) connected to the clear liquid outlet of the secondary high-precision membrane filter (26) and connected to the resin impurity removal device (3).

5. The system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid process according to claim 4, It is characterized in that The chemical impurity removal system (2) also includes an impurity removal slag stirring and washing tank (28) connected to the solid phase outlet of the first press (21) and the solid phase outlet of the second press (25), and a press C (29) connected to the impurity removal slag stirring and washing tank (28).

6. The system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid process according to claim 5, It is characterized in that The liquid phase outlet of the press C (29) is connected to the pulping system (1), the solid phase outlet of the press C (29) is connected to a slag removal external transmission line (30), and the slag removal stirring and washing tank (28) is connected to a process water transmission pipeline B (31).

7. The system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid process according to claim 4, It is characterized in that The pH adjusting tank A (19) is connected to a first alkali material conveying line (20), and the pH adjusting tank B (23) is connected to a second alkali material conveying line (24).

8. The system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid process according to claim 4, It is characterized in that The concentrated liquid phase outlet of the first-stage high-precision membrane filter (22) is connected to the first-stage press (21).

9. The system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid process according to claim 4, It is characterized in that The concentrated liquid phase outlet of the secondary high-precision membrane filter (26) is connected to the secondary press (25).

10. The system for producing lithium carbonate and by-producing high-purity potassium sulfate by acidifying clinker with sulfuric acid process according to claim 1, It is characterized in that It also includes a purified liquid storage tank (32) which is connected from the resin impurity removal device (3) and connected to the MVR evaporator (4).

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