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With the semiconductor industry currently undergoing sustained expansion, there is strong market demand for tin as a key raw material for solder. Given the tight global supply of tin resources, efficient beneficiation and recovery have become crucial for mines to improve quality and enhance efficiency. Tin ore beneficiation constitutes a coherent and comprehensive system, with each stage directly influencing the final concentrate grade and resource utilisation rate.
After extraction, the raw ore is first fed into the crushing and screening stage. Depending on the type of ore, a two-stage or three-stage closed-circuit process is employed. The ore is crushed to the appropriate particle size using jaw and cone crushers; following classification by vibrating screens, coarse particles are returned for secondary crushing, whilst fine material is sent to the grinding stage. Tin ore is brittle in nature and highly prone to clayification. The grinding process strictly adheres to the principles of staged grinding, staged separation and avoidance of over-grinding. Various types of ball mills and hydrocyclones are utilised to control the fineness of the grind. For raw ore with a high clay content, a pre-washing operation is carried out to remove surface clay, thereby preventing fine clay particles from interfering with subsequent separation processes.
As cassiterite has a density far higher than that of associated gangue minerals, the industry generally adopts a combined separation process centred on gravity separation, supplemented by flotation and magnetic separation. Jigging machines are used for the rough selection of coarse-grained tin, whilst shaking tables are employed for the fine selection of fine-grained material; a combination of multi-stage grinding and gravity separation can enhance the overall recovery rate; Flotation is specifically employed to recover ultrafine cassiterite that is difficult to retain via gravity separation, relying on various collectors and depressants to separate tin from silicate, calcium and magnesium impurities; magnetic separation, meanwhile, removes magnetic associated minerals such as iron and tungsten from the ore, thereby reducing the impurity content in the concentrate.
The tin concentrate produced through these separation processes undergoes dewatering via sedimentation, filtration and, where necessary, thorough drying. Tailings are primarily categorised into dry and wet types and are stored appropriately. Currently, many mines are simultaneously undertaking tailings re-processing to recover residual tin metal from the tailings, thereby further enhancing resource utilisation.
Adopting underground mining technology, Xinhai delivers one-stop full-cycle services for the project, including key underground infrastructure such as shaft construction and ramp development, as well as subsequent mining and ore haulage operations.
For disseminated copper-sulphide ores, a priority flotation process is employed, whereby copper is floated first, followed by sulphur flotation of the tailings. To reduce sulphuric acid consumption during sulphur flotation and ensure safe operation, process conditions with low alkalinity should be used as far as possible during copper flotation.
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