Global process for obtaining lithium sulfate monohydrate ore with low contents of impurities associated with chlorine and magnesium

Abstract

This patent application refers to a global process to obtain lithium sulfate monohydrate ore with low contents of impurities associated to chlorine and magnesium; in particular, the process consists of the concentration, through grinding, flotation, leaching and filtration stages, of the lithium sulfate present in potassium Carnallite (KCl*MgCl2*6H2O) stockpiles with high contents of lithium sulfate (Li2SO4*H2O) and sodium chloride (NaCl). The greatest advantage of the invention's process is that it uses salts and brines which are not currently being processed today and which have already been extracted far potassium production.

1 . Process to obtain lithium sulfate monohydrate ore with low contents of impurities associated to chlorine and magnesium, from brines which were not financially attractive, in order to exploit them far the production of Lithium, CHARACTERIZED by comprising three main stages; grinding, flotation, and leaching; where, in order to carry out the first stage, potassium carnallite salts with a high concentration of SO4 are fed to a comminution stage, specifically grinding, in order to reduce their size and release the lithium sulfate present in the ore; in which the material obtained from the grinding is subjected to a Rougher flotation stage, the purpose of which is to recover the highest quantity of material of interest as possible, favoring recovery over the mineral's grade; where the concentrate that is generated in the Rougher flotation stage enters a Cleaner flotation stage or a cleaning stage, in which a concentrate with the required purity is obtained, in order to be fed to a leaching stage; in which the concentrate obtained in said Cleaner flotation or cleaning stage is subjected to a leaching stage, where said concentrate from the Cleaner flotation or cleaning stage is added along with water, at a ratio of 0.3 water/solid. 
     
     
         2 . Process to obtain lithium sulfate monohydrate ore with low contents of impurities, in accordance with  claim 1 , CHARACTERIZED because, after said filtering stage, it includes subjecting the resulting concentrate to washing, adding water at a ratio of 0.14 water/solid in order to displace the remaining impurities and impregnation, increasing the grade of the lithium sulfate monohydrate concentrate to over 95% purity 
     
     
         3 . Process to obtain lithium sulfate monohydrate ore with low contents of impurities, in accordance with  claim 1 , CHARACTERIZED because tailings are generated in said Cleaner flotation, which are recirculated to said Rougher flotation, in order to recover the material that was not floated in the circuit; in which said Rougher flotation generates tailings that are inserted into a second recuperative stage, which consists of a Scavenger flotation, the purpose of which is to increase the overall recovery of the flotation circuit, recovering the material which could not float during the previous stage, obtaining tailings exhausted in lithium sulfate with a grade of 0.2% Li. 
     
     
         4 . Process to obtain lithium sulfate monohydrate ore with low contents of impurities, in accordance with  claim 1 , CHARACTERIZED because said grinding of the material is carried out in a collapse crusher and cage mills, with the objective of releasing the lithium sulfate crystals present in said potassium carnallite matrix and preparing them far said Rougher flotation. 
     
     
         5 . Process to obtain lithium sulfate monohydrate ore with low contents of impurities, in accordance with  claim 4 , CHARACTERIZED because a previously saturated and balanced brine is added to the mill shells of the cage mill, removing possible solids embedded therein. 
     
     
         6 . Process to obtain lithium sulfate monohydrate ore with low contents of impurities, in accordance with  claim 1 , CHARACTERIZED because, after said grinding stage, said salts come into contact with a brine previously saturated and balanced with the same salts, generating a pulp with a high percentage of solids (40-50%), where 50% of flotation reagent (amine collector) is added to condition the obtained material. 
     
     
         7 . Process to obtain lithium sulfate monohydrate ore with low contents of impurities, in accordance with  claim 1 , CHARACTERIZED because the recirculation flow of the tailings from the Cleaner flotation stage and Scavenger flotation concentrate are added to the Rougher flotation, thus generating a pulp of approximately 30-35% solids to feed the Rougher flotation. Also, the remaining 30% of the collector and frothier is added to a cell where said Rougher flotation is carried out. 
     
     
         8 . Process to obtain lithium sulfate monohydrate ore with low contents of impurities, in accordance with  claim 1 , CHARACTERIZED because said Rougher flotation operates in a recuperative way, obtaining lithium sulfate monohydrates above 50%, in which the Rougher flotation tailings, with low sulfate monohydrate contents, go through a classification and regrinding stage in cage mills. 
     
     
         9 . Process to obtain lithium sulfate monohydrate ore with low contents of impurities, in accordance with  claim 8 , CHARACTERIZED because the reground and small size material extracted from said classification is pooled together to become the feed to the Scavenger flotation stage, along with the remaining percentage of collector and frothier, where plant tailings are generated with the lowest levels of lithium sulfate. 
     
     
         10 . Process to obtain lithium sulfate monohydrate ore with low contents of impurities, in accordance with  claim 1 , CHARACTERIZED because the obtained Rougher concentrate, which is subjected to said Cleaner flotation stage, is concentrated to levels of 85% lithium Sulfate. 
     
     
         11 . Process to obtain lithium sulfate monohydrate ore with low contents of impurities, in accordance with  claim 8 , CHARACTERIZED because the material obtained from the cleaner flotation stage is subjected to a filtration stage, where a pile with a high content of lithium sulfate<85% is obtained.