Bornite Flotation - Test Conclusions
Bornite presents a high grade of oxidation that trend to decrease its Floatability requiring higher dosages of collector in order to get good flotation. This is confirmed by Parreira et. al. (5) with the Copper ore from Salobo, Carajas where is necessary high dosages of Potassium Amilic Xanthate (240 g/t) in order to get a recovery of 86% when head assays Cu 1.1%.
Bornite presents a high grade of oxidation that trend to decrease its Floatability requiring higher dosages of collector in order to get good flotation. This is confirmed by Parreira et. al. (5) with the Copper ore from Salobo, Carajas where is necessary high dosages of Potassium Amilic Xanthate (240 g/t) in order to get a recovery of 86% when head assays Cu 1.1%.
Bornite flotation changes while superficial oxidation grows probably to the layers of iron oxides formed on its surface. This affirmation coincides with Zachwieja et. al. (6). These layers are hydrophilic and it is necessary a high dosage of collector so that get an initial equilibrium and then make weak the hydrophilic properties on mineral surface. Thus, can be possible produce the necessary dixanthogen for Bornite flotation.
Superficial oxidation can be diminished using a previous treatment of sulphidisation which can has the following mechanism (4).
4Cu2S.2CuS.Fe2O3 + 2HS- = 2(2Cu2S.CuS.FeS) + 2 OH- + ½ O2
From a thermodynamic viewpoint is possible that oxidation can be generated through FeS because iron has more affinity for oxygen.
Floatability of Bornite without oxidation is easy and can occur on low dosages of collector. This floatability can be affected if pH is higher than 10 and can be depressed more than chalcocite and chalcopyrite. Its behaviour probably is similar to pyrite whose depression mechanism on alkaline pH occurs by hydrolysis. Thus, can be considered that the floatability of Bornite in a very alkaline pH is reduced by similar reasons producing a new superficial oxidation that make difficult collector adsorption.
Reaction between cupric ion and xanthate occurs according the following reaction:
- Cu+2 + 2X- = ½ Cu2X2 + ½ X2
Sodium sulphide reacts with oxygen forming thiosulphate, sulphites and sulphate ions resulting a consume of reagent until oxygen can be saturated, and then can be formed a new fresh sulphide surface.
According to Molina and Vega (4), such reaction occurs with intervention of cupric ions and soluble copper released during superficial oxidation:
2xCu2S. yCuS. FeS + ½ O2+ H2O = (2x-1)Cu2S.(y+1) CuS. FeS + 2 OH- + Cu+2
Thus, xanthate can be chemiadsorbed in the form of Cu2X2 and physically like X2. Iron has active participation in the latter reaction.
Cuprous xanthate and dixanthogen are the agents that promote hydrophobicity and consequently floatability.
Readsorption effect occurs when HS- is consumed. According to Clark et. al. (7) can exist more than one mechanism that motives sodium sulphide consumption. There are mechanisms of chemiadsorption and catalytic oxidation of HS- to sulphates, sulphites and thiosulphates. These mechanisms occur quickly because HS- is consumed very fast.
REFERENCES.
- A. Betejtin. Curso de Mineralogia. Moscu. Ed. MIR. 223-224. 1977.
- B. Grguric, A. Putnis, R. Harrison. An Investigation of the Phase Transitions in Bornite Using Neutron Diffraction and Differential Scanning Calorimetry. American Mineralogist. Vol.83. 1231-1239. 1988.
- A.N. Buckley, I.C. Hamilton, R. Woods. Investigation of the Surface Oxidation of Sulphide Minerals by Linear Potencial Sweep Voltammetry and X-Ray Photoelectron Spectroscopy. E. Forsberg. Flotation of Sulphide Minerals, 41-59, 1985.
- H. Vega, E. Molina. Caracterización de la Flotabilidad de la Bornita. Minerales.Vol. 38, 31-36, 1983.
- E. Parreira, E. Clark, R. Lima. Salobo Copper Ore Process Development. G.S. Dobby et. al. Mineral Processing and Process Control. New York, 133-144, 1991.
- J.B. Zachwieja, G.W. Walker, P.E. Richardson. Electrochemical Flotation of Sulphides: the Bornite-Ethilxanthate System. Minerals and Metallurgical Processing. Vol. 4. No 3, 146-151. 1987.
- D.W. Clark, A.J.H. Newell, G.F. Chilman and P.G. Capps. Improving Flotation Recovery of Copper Sulphides By Nitrogen Gas and Sulphidisation Conditioning. Minerals Engineering. Vol. 13, No. 12, 1197-1206. 2000.
Identifying Sodium Minerals GOLD MINERALOGY AND FLOTATION Refining Use Quality Crusher Parts The Common Rock-Making Minerals Epithermal Veins Acid and Basic Phosphates - Olivenite and Lazulite Composition Common Rock Types Forged Steel Grinding Balls (new) Newhouse Crusher -high-speed class fine-reduction crusher Gibbsite - Hydrargillite and Psilomelane Composition & Structure XANTHATES Brucite Composition, Crystallization & Structure Typical Exploration Drilling Pattern Exploration Sampling Program
