Summary of lithium extraction process from ore

The main methods for extracting lithium from ores include sulfuric acid method, sulfate method, 

lime sintering method, chlorination roasting method, and soda ash pressure boiling method. 

These lithium extraction processes for ores all involve a spodumene grinding process. Guilin Hongcheng is a manufacturer of lithium ore grinding machines. 

Today, we will summarize and introduce the process of lithium extraction from ores 

and the application of spodumene grinding powder in lithium extraction from spodumene.

1、 Sulfuric acid method

The sulfuric acid method for extracting lithium carbonate from spodumene is currently a relatively mature process for extracting lithium from ores. 

This method first roasts natural spodumene at 950-1100 ℃, transforming it from monoclinic α - spodumene to tetragonal β - spodumene. 

Due to the crystal transformation, the physical and chemical properties of the mineral also undergo significant changes with the crystal structure, 

increasing its chemical activity and allowing it to react with acids and bases in various ways. The operation steps are as follows:

① Roasting: Weigh a certain amount of spodumene and place it in a rotary kiln at 1000-1100 ℃ for 30 minutes to roast;

② Lithium pyroxene powder: ground to below 200 mesh using a lithium ore mill;

③ Acid roasting, with sulfuric acid (93% -98%) dosage of 140% of the theoretical dosage, roasting temperature of 250 ℃, and roasting time of 30 minutes;

④ Water immersion, stirring and leaching the acidified clinker with deionized water;

⑤ After separation and leaching, add CaCO to quickly neutralize to around pH, 

allowing some iron and aluminum to enter the slag, and filter to obtain the leaching solution; 

After purification, the leachate can be used for the extraction of lithium carbonate.

2、 Sulfate method

The sulfate method is to sinter potassium sulfate with natural spodumene to convert lithium in the ore into lithium sulfate, 

which can be dissolved from the ore into the solution through clinker leaching. The specific operation steps are as follows:

① The optimized conditions for the roasting stage are: temperature of 940 ℃, time of 120 min, and a ratio of lithium mica: KSO: NaSO: CaO=20:24:24;

② Extraction, first step: water immersion. Dissolve the roasted product in water at a liquid-solid ratio of 3:1, stir for half an hour, and then let it stand and filter. 

Perform three-stage leaching on the filter residue and combine the filtrate; Step 2: Acid leaching. 

Due to water leaching, 80% Li, 80% Na, and 30% potassium enter the solution, requiring further acid leaching to improve the leaching rate of Li. 

The leaching operation is the same as above, using three-stage acid leaching with a liquid-solid ratio of 3:l;

③ During the process of adjusting the pH of the leaching solution, it was found that white flocculent Al (OH) precipitates began to appear when pH>6. 

When pH>8, this white precipitate no longer increased, indicating that Al (OH) 3 had almost completely precipitated. 

Continue to add alkali to increase pH. When pH>10, reddish brown Fe (OH) 3 begins to appear. 

When the pH is greater than 13, the reddish brown precipitate no longer increases, indicating that Fe (OH) 3 is almost completely precipitated. 

Filter and obtain purified liquid.

④ Lithium deposition, heat the solution to around 95 ℃, and add Na2CO3. Solution, white powder precipitate is produced in the solution. 

After filtration, a filter cake with a thickness of about 1cm is formed on the filter paper. 

After washing with hot water three times, the filter cake is dried in a 200 ℃ oven for 3 hours, weighed, and dissolved in 60mL of dilute sulfuric acid solution for testing. 

Collect the filtrate and leave it for testing.

3、 Lime sintering method

The lime sintering method is to sinter lime or limestone with lithium containing ore, and then dissolve the sintered block to produce lithium carbonate. 

The process includes several main steps such as raw material preparation, roasting, leaching, washing, leachate concentration, purification, crystallization, etc. 

After fine grinding, limestone is proportioned according to the mass ratio of lithium minerals to limestone, 

and mixed with a certain amount of calcium oxide to form qualified raw materials. 

The raw materials are then placed in a rotary kiln for reaction at a certain temperature, converting lithium in the minerals into water-soluble compounds. 

The burnt product is removed from insoluble impurities through a leaching process, 

and then filtered and separated to obtain a leaching solution mainly composed of lithium compounds. 

CO2 gas, waste furnace gas, or sodium carbonate is introduced into the leaching solution to precipitate lithium in the form of insoluble carbonate. 

After washing and drying, lithium carbonate product is obtained.

4、 Chlorination roasting method

The chlorination roasting method is the use of chlorinating agents to convert lithium and other valuable metals in ores into chlorides, 

thereby extracting metals and their compounds. 

The process steps for extracting lithium by chlorination roasting method are as follows:

① Ingredients: lithium mica: NaCl: NaCl=1:1 ratio is fed into a lithium ore mill for grinding, evenly mixed to obtain qualified raw materials, and made into pellets;

② Roasting, control the temperature between 900-950 ℃ during the roasting process;

③ Water immersion, the flow ratio of leachate to clinker is, at room temperature;

④ To remove calcium, calculate the reaction CaCl+Na2CO3=CaCO3+2NaCl based on the content of calcium ions in the leachate. 

Add an excess of 2% to solid Na2CO3 powder or returned lithium mother liquor, and react at 90-95 ℃;

⑤ Evaporate and precipitate NaCl;

⑥ Cooling precipitation;

⑦ Sinking lithium.

5、 Soda ash boiling method

The soda ash pressure boiling method mainly includes four processes:

 crystal transformation roasting, pressure boiling, carbonization leaching, and lithium precipitation. 

The steps are as follows:

① Roasting transformation: Take 100g of fly ash sample, place it in a muffle furnace, and carry out transformation roasting at high temperature. 

The temperature of roasting transformation is controlled at 1150~1250 ℃;

② Lithium pyroxene grinding powder: Grind the roasted raw materials to 50-325 mesh using a lithium ore grinding machine;

③ Slurry mixing: Mix Na2CO3 and the finely ground clinker with the corresponding amount of water to form a slurry;

④ Pressure immersion: using high-pressure steam to heat the slurry, raising its temperature to 180-270 ℃, 

and maintaining a constant temperature and pressure for~, the pressure of the high-pressure steam is~6Mpa;

⑤ Cooling and pressure reduction: Reduce the pressure of the slurry in step 4 to atmospheric pressure and lower its temperature to 0-40 ℃;

⑥ Carbonization: CO2 is introduced into the boiling slurry in step 5 to convert lithium carbonate into lithium bicarbonate with high solubility. 

The carbonization temperature of the boiling slurry is controlled between 0-40 ℃, the carbonization pressure is around 4 Mpa, the liquid-solid ratio is 2-6, and the holding time is 1-2 hours. 

This process is carried out in a carbonization kettle;

⑦ Separation, washing, and impurity removal: Filter the carbonized slurry from step 6 to obtain a filtrate and filter residue. 

Discard the filter residue after three washes, and use chelating resin to remove impurities such as calcium and magnesium from the filtrate;

⑧ Heating decomposition: Heat the purified solution after impurity removal in step 7 at a decomposition temperature of 50-100 ℃ to obtain lithium carbonate slurry;

⑨ Separate washing: Place the lithium carbonate slurry obtained in step 8 into a centrifuge for dehydration to obtain lithium carbonate wet material, 

then wash it again, dehydrate it again, and repeat washing 2-6 times;

⑩ Drying: Dry the lithium carbonate wet material obtained in step 9 in an oven at a temperature of 150-250 ℃ for 2-3 hours to obtain the battery and lithium carbonate.