Application Guide: Benzohydroxamic Acid (BHA) & Salicylhydroxamic Acid (SHA) Collectors
Hydroxamic acid reagents are important collectors for oxide ores and refractory minerals, offering unique selective collecting ability on oxygen-bearing metal minerals. Among them, Benzohydroxamic Acid (BHA) and Salicylhydroxamic Acid (SHA) are the two most widely used products.
1. Benzohydroxamic Acid (BHA)
Benzohydroxamic Acid is an aromatic hydroxamic acid collector with strong collecting power and good selectivity. It collects target minerals through chelation adsorption between the hydroxamic group and metal ions on the mineral surface.
Applicable minerals:
Copper oxide ores: malachite, chrysocolla, etc.
Rare earth ores: bastnaesite, monazite, etc.
Cassiterite (tin ore)
Scheelite (tungsten ore)
Ilmenite and certain refractory sulfide ores
Application method:
BHA has poor solubility in cold water. Prepare it as a solution by dissolving in sodium hydroxide (commonly 3%-10% concentration); gentle heating helps dissolution;
Flotation pH is generally controlled at 7-9 (neutral to slightly alkaline conditions give best performance);
Typical dosage: 100-800 g per tonne of ore, to be determined by ore characteristics and flotation tests;
Use together with frothers (e.g., Pine Oil No.2, MIBC); modifiers may be added to improve selectivity when necessary.
2. Salicylhydroxamic Acid (SHA)
Salicylhydroxamic Acid is also an aromatic hydroxamic acid collector. Its molecule contains both phenolic hydroxyl and hydroxamic groups, giving strong chelating ability toward calcium, iron, tin and rare earth ions, with better selectivity than common fatty acid collectors.
Applicable minerals:
Rare earth ores: bastnaesite, monazite
Cassiterite and tungsten ores
Copper oxide ores, ilmenite
Calcium- and iron-bearing mineral systems
Application method:
SHA has low solubility; dissolve it with sodium hydroxide or hot water before use;
Suitable pH range is relatively wide, generally 6-9, adjustable according to mineral type;
Typical dosage: 50-500 g per tonne of ore, depending on ore grade and characteristics;
Combining SHA with BHA or other collectors often improves both recovery and selectivity.
3. Key Application Notes
Dissolution is essential: Hydroxamic acid reagents have poor water solubility and must be pre-dissolved into solution. Direct dry addition often leads to poor dispersion and unstable results;
Reagent regime: Recommended addition order: adjust pH first, then add collector, then frother, to ensure full interaction between reagents and minerals;
Dosage control: Overdosing reduces selectivity while underdosing lowers recovery. Determine the optimum dosage through bench-scale flotation tests;
Synergistic combination: Blending BHA with SHA, or combining with xanthate collectors, can improve overall recovery for complex ores;
Storage: Keep hydroxamic acid reagents sealed, dry and away from light to prevent moisture absorption, caking and oxidation.
Bitop Bihope Qingdao Mining Co., Ltd. specializes in supplying mineral processing reagents. Our hydroxamic acid collectors offer stable quality and timely delivery. Customers are welcome to contact us for samples and trials.
