Three Mineral Processing Methods for Lithium-Rich Ores

As a strategic resource in the new energy sector, demand for lithium continues to rise. It is primarily sourced from lithium-rich ores such as spodumene, lithium mica and lithium-phosphate-aluminate. The mineralogical characteristics of different lithium-rich ores vary significantly, and the corresponding mineral processing methods each have their own specific focus. The following provides a detailed explanation of the core mineral processing methods for these three types of ore.

Spodumene ore is primarily processed using flotation, supplemented by magnetic separation and gravity separation for impurity removal. Flotation is divided into two types: direct flotation and reverse flotation. Ordinate flotation is conducted in an alkaline medium. Following desliming through high-concentration, vigorous agitation, a ‘three alkalis and two soaps’ reagent combination is employed: sodium hydroxide, sodium carbonate and sodium sulphide as modifiers, and paraffin wax soap and naphthenic acid soap as collectors, to achieve the separation of spodumene from gangue minerals; Reverse flotation, on the other hand, utilises lime to create an alkaline environment, employing starch and dextrin to suppress spodumene, whilst using amine collectors to float the gangue, with the spodumene concentrate retained in the retention tank.

The core of lithium mica ore beneficiation is flotation; due to its naturally good floatability, conventional flotation is widely applied. During beneficiation, suitable collectors must be selected; anionic fatty acid-based, amphoteric combination, or cationic amine-based collectors are all applicable, with octadecylamine performing exceptionally well in acidic and neutral media. Unactivated lithium mica is difficult to capture using oleic acid-based collectors and requires pre-treatment with activators such as hydrofluoric acid to enhance its floatability. Following flotation, the product undergoes washing, concentration and drying to yield high-grade lithium concentrate.

The beneficiation of lithium-phosphate-aluminate employs a combined ‘flotation + leaching’ process. First, lithium-phosphate-aluminite concentrate is obtained through flotation. Following grinding and pre-treatment, the concentrate is leached with concentrated sulphuric acid to convert lithium and aluminium into soluble sulphates, whilst simultaneously extracting fluorides and phosphates. Limestone and lime are added to the leachate to neutralise acidic impurities, and harmful components are removed through precipitation, ultimately yielding a lithium salt product.

In the actual mineral processing process, beneficiation tests must be conducted based on the specific properties of the ore, and process parameters and reagent regimes must be optimised accordingly to achieve efficient recovery of lithium resources.