Pourquoi la flottation de la cassitérite est-elle nécessaire ?

Résumé

Tin mining primarily relies on cassiterite (SnO₂), which accounts for most industrial tin production. While séparation par gravité is the dominant beneficiation method due to cassiterite’s high density (6.4–7.1 g/cm³), its brittle nature leads to significant slime formation during crushing and grinding. Consequently, flottation becomes essential for recovering fine-grained cassiterite from re-election tailings and slimes. This article explores cassiterite flotation techniques, including optimal collectors, pH control, and environmental considerations in modern practices.

The Necessity of Cassiterite Flotation

Challenges in Cassiterite Beneficiation

• Natural Brittleness – Cassiterite readily forms slimes (<0.04 mm) during mining and processing, rendering gravity separation inefficient for fine particles.
• Complex Ore Compositions – Tin ores often contain sulfide minerals (e.g., pyrrhotite, arsenopyrite) and silicate gangue, requiring selective separation.
• Economic & Environmental Drivers – Flotation recovers tin from low-grade tailings (0.3–1.5% Sn), reducing waste and improving resource utilization.

Key Flotation Parameters

1. Collectors

Various fatty acids and their soaps easily capture cassiterite. Therefore, collectors can use oleic acid, tar oil, oxidized white wax soap, nylon 1010 bottom, alkyl sulfate, alkyl sulfonate, sulfosuccinate, etc. Experimental studies have shown that cassiterite flotation with formazan, benzylic acid, and ethylene sometimes yields better results.

2. pH Optimization

• Acide oléique : la valeur du pH est généralement comprise entre 9,0 et 9,5.
• A: The pH value of the rough selection is generally 5~6, and it can reduce the pH value of the selected one to 2.5~4.0.
• When adjusting the pH of pulp, chemicals such as sodium carbonate and sulfuric acid are often used.
• During cassiterite flotation, to suppress the associated silicate ore, calcium magnesium ore, and wolframite, water glass, sodium hexametaphosphate, carboxymethyl cellulose, and oxalic acid.

3. Feed Preparation

• Pre-remove ultrafines (<0.01 mm) to reduce reagent consumption. The flotation material is generally gravity tailings less than 0.04mm, and the sludge less than 0.01mm is removed first.
• Desulfurize sulfide-rich ores avant tin flotation to avoid concentrate contamination. If the flotation ore is vein tin ore, it is often accompanied by sulfide deposits of iron, arsenic, antimony, lead, copper, zinc, and other metals. At this moment, it should first use the sulfide deposit activator to separate the sulfide deposit. Then, flotation of cassiterite to avoid sulfide contamination of the cassiterite concentrate.

Usine de flottation de cassitérite

The raw ore of tin ore is a high and medium-temperature hydrothermal cassiterite sulfide deposit. The composition of mineral deposits is messy. Metal deposits include pyrrhotite, magnetite, arsenopyrite, bismuthite, galena, sphalerite, chalcopyrite, etc. Non-metal deposits include carbonate, silicic acid, etc., salts, and halides. Cassiterite is yellowish-brown and black and is embedded in fine particles. Most of it is embedded in pyrrhotite in powder form, and a small part is scattered in magnetite and skarn deposits in granular form. The largest grain is 0.55mm, and the smallest is 0.002mm, generally between 0.15~0.02mm.

The feed of cassiterite flotation is the tailings after desulfurization, iron removal, and shaking table processing. The tailings of the table à secousses entrent dans l'épaississeur pour la déshydratation et vont dans le centrifugeuse. Le concentré de la centrifugeuse est ensuite évacué par l'installation de traitement des eaux usées. épaississeur et l'alimente ensuite en réservoir de mélange pour l'ajout de médicaments et la réduction en pâte. Il utilise l'acide salicylique comme collecteur, le carbonate de sodium pour ajuster le pH de la pâte à 7~8, la gomme de mûrier comme dépresseur et l'huile n° 2 comme agent moussant. Le concentré d'étain est sélectionné par le premier balayage grossier, le deuxième balayage, le troisième balayage fin et le premier balayage fin. Le minerai brut contient 1,0% 6~1,3% d'étain, la teneur du concentré de flottation est de 1,3%~16%, et le taux de récupération est de 72%~76%.

The practice has shown that low-toxic salicylic enteric acid can completely replace the highly toxic swollen acid, significantly reducing the environmental pollution problems in the production and use of pharmaceuticals.

The flotation function for tin extraction from tin sludge and smelting slag: it has excellent collection and selectivity. It can replace the traditional medicament benzyl swollen acid for tin selection, overcoming the defects of benzylic swollen acid, such as preciousness and high toxicity.

Dosage proposé : 400-800 g/tonne alimentation
La méthode de fabrication est la suivante a 2-5% aqueous solution (weight ratio), dissolved with 40C warm water.
Champ d'application : Boues d'étain de faible qualité et scories de fusion, qui peuvent produire 1,5% d'étain à température ambiante (température minimale de 5°C) pour sélectionner plus de 40% de poudre de concentré d'étain, avec un taux de récupération de plus de 70%.
Fonction de protection de l'environnement : L'agent est peu toxique, respectueux de l'homme et de l'environnement et facilement biodégradable.

Caractéristiques du produit

1. Propriétés : Le produit est un solide poudreux de couleur rose à rouge-orange, légèrement soluble dans l'eau, facilement soluble dans une solution alcaline et stable.
2. New agent for selection efficiency.
3. La norme pharmaceutique est simple et le coût est faible ;
4. Respectueux de l'environnement.

Dans certaines conditions, les collecteurs combinés présentent une bonne sélectivité. Ce produit peut former des chélates stables avec étain, tungstène, terres rares, cuivre, fer, and other metals. And it forms unstable chelates with alkaline earth metals and alkali metals. Therefore, the combination drug used in the flotation operation of some metal deposits can get a good separation effect. A combination of medications with flotation weight can achieve a very excellent result. Generally, the total recovery can reach more than 85%.

Conclusion

Cassiterite flotation is indispensable for maximizing tin recovery from fine-grained or complex ores where gravity methods fail. Advances in collector chemistry (e.g., eco-friendly chelating agents) and process optimization have made flotation both economically viable and environmentally sustainable. Future developments may focus on AI-driven reagent dosing and hybrid gravity-flotation circuits to further enhance efficiency.

Key Takeaway: Flotation transforms marginal tin resources into profitable reserves while mitigating mining’s ecological footprint.