Processes for preparing lithium carbonate

A system for preparing lithium sulphate, the system comprising:

• a first reactor,
• the first reactor comprising at least one inlet for receiving an acid roasted lithium-containing material, and at least one second inlet for receiving water, wherein the lithium-containing material is a material that has been previously reacted with H2SO4, and
• the first reactor configured to contain a first slurry, the first slurry comprising a solid and an aqueous composition comprising Li+ and at least one metal ion;
• a second reactor,
• the second reactor being in in fluid communication with the first reactor, and configured to receive at least a portion of the first slurry or at least a portion of the aqueous composition comprising Li+ and at least one metal ion and to contain a second slurry, the second slurry comprising a first precipitate comprising at least one hydroxide of the at least one metal ion and an aqueous composition comprising Li+ and having a reduced amount of the at least one metal ion,
• the second reactor comprising at least one inlet for receiving a base, and being fitted with a first pH probe, a first oxidation reduction potential (ORP) probe, and a sparger in fluid communication with the second reactor,
• the sparger being configured to sparge a gas into the second reactor,
• the first pH probe being configured to at least substantially maintain pH in the second reactor at about 4.5 to about 6.5, and
• the first ORP probe being configured to at least substantially maintain ORP at about or above 350 mV;
• a first filter,
• the first filter being in fluid communication with the second reactor to receive at least a portion of the second slurry and being configured to separate the first precipitate from the aqueous composition comprising Li+ and having a reduced amount of the at least one metal ion;
• a third reactor,
• the third reactor being in fluid communication with the first filter to receive at least a portion of the aqueous composition comprising Li+ and having a reduced amount of the at least one metal ion;
• the third reactor comprising at least one inlet for receiving a second base and being fitted with a second pH probe;
• the second pH probe being configured to at least substantially maintain pH in the third reactor at about 9.5 to about 11.5,
• the third reactor further comprising at least one inlet for receiving at least one metal carbonate, and
• the third reactor being configured to contain a third slurry, the third slurry comprising a second precipitate comprising at least one carbonate of the at least one metal ion and an aqueous composition comprising Li+ and having a further reduced amount of the at least one metal ion;
• a second filter,
• the second filter being in fluid communication with the third reactor to receive at least a portion of the third slurry and being configured to separate the second precipitate from the aqueous composition comprising Li+ and having a further reduced amount of the at least one metal ion;
• and
• a fourth reactor,
• the fourth reactor in fluid communication with the second filter to receive at least a portion of the aqueous composition comprising Li+ and having a further reduced amount of the at least one metal ion, and
• the fourth reactor comprising an ion exchange resin, the ion exchange resin being configured to contact the aqueous composition comprising Li+ and having a further reduced amount of the at least one metal ion and thereby to remove the at least one metal ion and to obtain an aqueous composition comprising lithium sulphate.