Tin recycling process

The following are the core methods and technical points of tin recycling process, classified and explained according to the characteristics of raw materials and recycling goals:

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 1、 Chemical method

Acid leaching method

 

Principle: Dissolve tin in waste with acid solution to generate soluble tin salts (such as tin sulfate), and then obtain metallic tin through displacement or electrolysis.

Scope of application: Waste materials with high tin content (such as tin slag and tin plating waste liquid).

Recovery rate:>90%, acidic waste liquid needs to be treated to prevent pollution.

Solvent extraction method

 

Principle: Selective organic solvents (such as tributyl phosphate) are used to extract tin ions, followed by back extraction and purification.

Advantages: Suitable for low concentration tin waste liquid (such as wastewater), with high recovery rate.

Low temperature reduction method

 

Technology: Using a carbon thermal reduction synergistic molten salt medium (NaCl KCl), SnO ₂ is reduced at 300-500 ℃.

Advantages: Energy consumption reduced by 65% (<1500kWh/ton), recovery rate of 97%, purity of 99.9%, suitable for low-grade tin slag (SnO ₂ 5-15%).

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 2、 Physical Law

Electrolytic method

 

Principle: Tin containing waste liquid is used as an electrolyte, and tin ions are reduced and deposited at the cathode.

Scope of application: High purity tin recycling (such as electronic waste), capable of processing waste tin containing impurities.

Melting method

 

Process: High temperature melting waste (>232 ℃), density separation of tin and impurities.

Key: Accurate temperature control (245 ± 5 ℃), preventing oxidation losses.

Gravity sorting

 

Application: After crushing and screening, tin particles (>0.1mm) are separated using shaking tables and jigs.

Scenario: Pre treatment of tin ore and smelting slag.

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 3、 Joint process (applicable to complex materials)

Re selection flotation combination

 

Process: Coarse grained reselection tailings → Fine grinding → Flotation recovery of fine cassiterite.

Effect: Comprehensive recovery rate increased by 15%, cost reduced by 20%.

Magnetic separation reselection combination

 

Application: Magnetic separation for iron/tungsten removal → reselection for tin extraction, suitable for iron bearing coexisting ores.

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 4、 Environmental Protection and Efficiency Enhancement Technologies

Biological Law

 

Principle: Microorganisms adsorb tin ions to form precipitates.

Current situation: Environmental protection but low recycling rate, technology waiting to mature.

Waste gas/liquid treatment

 

Requirement: Acidic waste liquid needs to be neutralized (pH 5-9), and exhaust gas should be adsorbed or catalytically converted by activated carbon (CO → CO ₂).

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 Key factors in process selection

Factor Explanation

Raw material characteristics: high tin waste → chemical method;

 Low grade/fine particles → flotation or low-temperature reduction;

 Containing iron/tungsten → magnetic separation combined

Cost control: Low temperature reduction has the lowest energy consumption, while biological methods have high costs but are environmentally friendly

Environmentally compliant exhaust gas requires CO catalytic conversion, and the concentration of heavy metals in the waste liquid is ≤ the environmental limit

Note: The current cutting-edge directions include supercritical CO ₂ separation coating, AI intelligent sorting, biological leaching and other technologies to improve the efficiency of complex waste recycling.