Processing of Mixed Tungsten Ore

Tungsten is an important rare metal that occurs naturally in a dispersed state and can only be mined after geological concentration has formed ore deposits. Over 20 types of tungsten minerals have been identified in nature, of which wolframite and scheelite possess the highest industrial value and currently constitute the primary sources of tungsten resources. Tungsten ore beneficiation primarily relies on physical separation, commonly employing processes such as pre-concentration, gravity separation, flotation and magnetic separation; for difficult-to-process intermediate products and low-grade concentrates, chemical beneficiation is employed as a supplementary measure to achieve efficient recovery.

Wolframite typically occurs in quartz vein deposits and is characterised by low grade, coarse grain size, high density, low hardness and a tendency to become slimy. The beneficiation process centres on gravity separation and comprises four main stages: pre-concentration, gravity separation, concentration and fine slime recovery. Prior to pre-concentration, ore washing, desliming and classification are carried out, typically using hand sorting, photoelectric sorting and heavy-medium separation, which can significantly improve the grade of the feed. Gravity separation typically employs a combination of jigs and shaking tables to process coarse-grained tungsten ore; magnetic separation can be used to assist in the recovery of weakly magnetic black tungsten ore; flotation is utilised for the recovery of fine-grained black tungsten slime. In flotation, low-toxicity, environmentally friendly isoxazoline-based collectors are prioritised, thereby avoiding the pollution and excessive costs associated with traditional reagents.

The beneficiation process for white tungsten ore is selected based on the types of associated gangue and the particle size of the ore. Coarse-grained white tungsten ore is processed using gravity separation, which offers the advantages of low cost, environmental friendliness and high recovery rates; fine-grained white tungsten ore is primarily processed by flotation. As white tungsten ore is often associated with sulphide minerals, these must be removed by flotation prior to beneficiation. Flotation is carried out in an alkaline medium; by adjusting the pulp pH and utilising specialised inhibitors and collectors, effective separation from calcium-bearing gangue minerals such as fluorite, calcite and barite is achieved. To enhance separation selectivity, a combination of silicate and metal salt inhibitors is frequently employed to improve the flotation performance of white tungsten ore.

Mixed tungsten ores, which consist of a combination of wolframite and scheelite, have a complex mineral composition and fine grain size distribution; a combined mixed flotation process is therefore frequently employed. First, sulphide minerals are removed by flotation, followed by the recovery of tungsten minerals via mixed flotation. Subsequently, magnetic separation, gravity separation or flotation are used to produce separate concentrates of wolframite and scheelite.

The processing route for tungsten ore must be determined based on the mineral type, distribution characteristics, association patterns and grade conditions. By developing a tailored process scheme through beneficiation testing, it is possible to effectively improve the grade and recovery rate of tungsten concentrate, thereby achieving efficient utilisation of tungsten resources.