Process for producing lithium carbonate from spodumene concentrate by sulfuric acid method

Abstract

The invention discloses a process for producing lithium carbonate from spodumene concentrate by a sulfuric acid method, and is used for solving the problems caused by the fact that lithium sulfate is leached in a strong acid environment in the existing lithium carbonate process. The process provided by the invention comprises the following steps: in a lithium sulfate preparation process, adding slag washing water and ground calcium carbonate in to a leaching tank and uniformly stirring, then, adding an acid clinker to uniformly stir to obtain a mixture, and filtering when the pH value of the mixture is 5.5-6.0 to obtain a lithium sulfate leachate, wherein the molar weight of ground calcium carbonate is greater than that of residual acid in the acid clinker. The process has the characteristics that neutralization reaction between the residual acid (sulfuric acid) in the acid clinker and ground calcium carbonate is firstly carried out, so that the lithium sulfate leaching environment is in a weak acid environment; the residual acid is prevented from reacting with oxides of Fe and Al in the material to reduce generation of gelatinous precipitates of Al(OH)3 and Fe(OH)3, so that the filtering performance is improved, the separating and filtering effect is improved and the water content in the filter cake (the filter residue) is effectively controlled, therefore, the output of lithium is reduced and the utilization of lithium is improved.

Description

technical field [0001] The invention belongs to the field of lithium carbonate produced by mine development, and in particular relates to a process for producing lithium carbonate by a sulfuric acid method of spodumene concentrate. Background technique [0002] At present, the sulfuric acid method is a production method commonly used to extract lithium salt from spodumene at home and abroad. The basic principle of this process is that sulfuric acid and β-spodumene undergo a replacement reaction at 250-300 ° C to generate Li 2 SO 4 . The reaction equation is as follows: [0003] β-Li 2 O·Al 2 o 3 4SiO2 2 +H 2 SO 4 → Li 2 SO 4 +H 2 O·Al 2 o 3 4SiO2 2 [0004] Disclosed a kind of method for manufacturing Lithium Retard as the patent of invention that application number is 201080065025.X, the method comprises the steps: [0005] (i) calcining α-spodumene ore or concentrate to generate β-spodumene; [0006] (ii) sulfating the β-spodumene at high temperature; ...

AI Technical Summary

Problems solved by technology

The existing lithium sulfate leaching process has the following problems: when the acid clinker enters the liquid phase, due to containing free sulfuric acid (residual acid), the sulfuric acid immediately reacts with oxides such as Fe and Al in the ore to generate ferric sulfate, while lithium sulfate also into the liquid phase

When heavy calcium is used to neutralize the free acid in the liquid phase, as the pH value increases, first Fe starts to hydrolyze, then Al starts to hydrolyze, and Al 3+ , Fe 3+ It is precipitated in the colloidal form of hydroxide, and when the pH value is 5.5-6, Fe 3+ and Al 3+ Completely hydrolyzed, this part of the hydrolyzed colloid will block the gap of the filter cloth during the separation process, resulting in a decrease in filtration performance, and it is not easy to separate the active ingredient lithium sulfate, which makes the water content of the filter cake increase, which is not conducive to washing and dehydration, and improves the lithium carry out amount, a serious waste of resources