How to extract lithium from spodumene?

15311826613

Welcome to consult Xinhai - customized mineral processing plan

Xinhai can provide you with mineral processing tests, mineral processing process and mineral processing equipment selection, mineral processing plant scheme design and construction drawing design; provide mining mineral processing equipment; provide mineral processing plant construction and equipment installation as well as mine management and operation services.

Consultation 153-1182-6613

15311826613

Click to add WeChat

Get product price

WeChat ID has been copied, add friends, and get manufacturer quotations!

In the process of lithium resource development and utilization, the processing and purification of lithium-containing minerals such as spodumene and lepidolite have long been carried out. At present, among the more than 130 known lithium-containing minerals, the processing and purification of lithium-containing minerals such as spodumene and lepidolite has long been carried out, and only a few silicate and phosphate minerals have economic value. This article takes spodumene (chain silicate) as an example to introduce its lithium extraction technology.

How to extract lithium from spodumene

Spodumene (LiAL[Si₂O₆]) has a high Li content (Li₂O₆%~9%) and is the main mineral source of lithium. Spodumene is a chain silicate mineral belonging to the monoclinic pyroxene mineral group, and silicon dioxide exists in tetrahedral form.

1. Sulfation treatment of spodumene

Due to the high stability of Li₂SO₄ in aqueous systems and its solubility, sulfation is one of the most commonly used technologies for processing spodumene to recover lithium. Other impurities (AL, NA, Mg and K) that are usually present in spodumene also form soluble compounds during the sulfation process, but lithium is slightly soluble in carbonate media, which helps to precipitate Li₂CO₃ from Li₂SO₄ dissolved in water.

For example: spodumene mineral is crushed and ground into a suitable particle size, then mixed with alkali metal sulfate (NA₂SO₄/K₂SO₄) and treated at 850~1200℃ to maximize lithium recovery. During the calcination process, Li is replaced by NA in NA₂SO₄, and Li₂SO₄ is formed through an ion exchange reaction (1170℃). Since the melting point of K2SO4 is higher than that of NA₂SO₄, a higher temperature is required for the ion exchange reaction to occur, but at higher temperatures, silica will decompose, resulting in a reaction that is not conducive to lithium recovery.

2. Carbonation treatment of spodumene

In the carbonation treatment, spodumene is mixed with NA₂CO₃ and heated at 525~675℃, so that the NA atoms of NA₂CO₃ replace the Li atoms, forming lithium carbonate and sodium aluminum silicate. In the presence of CO₂, the roasted product is leached with water to precipitate and separate lithium in the form of Li₂CO₃.

Before Li2CO3 is produced, the formation of LiHCO3 is an important step. Since the solubility of Li₂CO₃ in water is very low, CO₂ gas needs to be injected to convert it into LiHCO₃ with higher solubility. Lithium bicarbonate exists at pH 6-8. High-pressure sterilization of the system in the presence of CO₂ at 250°C can increase the solubility of LiHCO₃ in the solution, thereby improving the process efficiency.

3. Chlorination of spodumene

Chlorination is also an effective purification method because CL₂ can react with metal oxides and silicates to form water-soluble chlorides. The chlorination treatment of lithium-containing ores can selectively extract lithium at high temperatures, but the process is complex and requires highly corrosion-resistant equipment. When the Si-AL-Li-O-CL system reaches equilibrium during the chlorination process, there is the possibility of forming solid or liquid LiCL and other solid products of AL and Si in different phases. In addition, in a fixed bed reactor, the chlorination of spodumene concentrate (7.25% Li₂O and 2% impurities Fe, CA, Mg) was carried out under the conditions of a total flow rate of 100ml/min, a CL₂ partial pressure of 0.2~1.0Atm (about 0.02~0.1MPA) and 1000~1100℃.

4. Fluoridation treatment of spodumene

Lithium recovery is carried out by leaching β-spodumene in liquid hydrofluoric acid. Under reasonable leaching conditions (temperature 75℃, 7% HF, stirring speed 330r/min, reaction time 10min), up to about 90% of Li can be recovered. Si and AL dissolved in HF are removed by reacting with NAOH to form NA₂SiF₆ and NA₃ALF₆ precipitates. At the same time, LiF is also converted into a soluble hydroxide form (LiOH) and evaporated until the lithium concentration reaches 20g/L. Finally, the solution is heated to 95℃ for 20min to precipitate lithium in the form of carbonate, and the unwashed Li₂CO₃ precipitate is obtained with a purity of 98%.