Surface Properties of Aqueous Fluorapatite and Maghemite with Reference to the Dephosphorization of Magnetite

The success of the dephosphorization by reverse flotation of fluorapatite is heavily depending on the proper control of surfaces and interfaces in the mixture of several solid phases suspended in the aqueous solution through which the air bubbles are being dispersed

Adsorption mechanism of diethyldithio carbamate on covellite, cuprite and tenorite

Adsorption of diethyldithiocarbamate (DTC) on covellite, cuprite and tenorite was investigated under different experimental conditions. The qualitative nature of surface species formed at the interface was examined by selective solvent extraction and UVvisible spectrophotometric techniques. The presence of surface species such ::lB [Cu(DTC)]+, Cu(DTC)2and Cu(I) DTC at different concentrations of the reagent and pH of the suspension was investigated. The results of this study indicate a surface reactionbetween DTC ligand molecules and surface copper sites. As a result of interaction with DTC, cations on the mineral surface are dislodged from the lattice and precipitated on the surface as copper dithiocarbamate complexes. Depending on the concentration of DTC, two types of copper complexes, i.e. [Cu(DTC)]+at low concentration and Cu(DTCh at higher concentration, are noted on copper(II) substrates, whereas on cuprite Cu(I) DTC was formed along with [Cu(DTC)]+ and Cu(DTCh. From the kinetic study, the overall adsorption was found to be mainly controlled by diffusion processes

Adsorption of thiol collectors on Chalcopyrite

Adsorption of diethyldithiocarbamate and ethylxanthate on chalcopyrite mineral surface was studied by static bed adsorption method. The qualitative nature of surface species was examined by selective solvent extraction and UV-visible spectroscopic technique.The results clearly indicate that the interaction between surface metal ions and thiols is chemical in nature. As a result of chemical interaction of ligand molecules, metal ions from mineral surface are dislodged from the lattice and precipitates of metal-ligand complexes were formed on the surface. Surface complexes were found to be identical to that of bulk complexes with metal-to-ligand ratio of 1:2

Electrokinetic studies on covellite, cuprite and tenorite

Detailed electrokinetic measurements are conduct.ed on synthetic covellite, cuprite and tenorite particles. The role of potential determining ions identical to that of the particle lattice is considered in addition to usual H+ and hydroxide ions. In the case of CuS, additional charge reversals are noticed between pH ~ 2.5 and < 6.0 in addition to the usual charge reversals that occur by direct hydrolysis in the socalled region of metal ion precipitation. Interaction of protons with hydrous mineral surface and the adsorption of desorbed or exces metal ions with protonated surface sites are explained by ion exchange mechanism. Effect of reducing environment and oxidation-reduction reactions o

Shear flocculation of quartz.

The present study deals with the shear flocculation of quartz in aqueous solutions of dodecylamine. Zetapotential data was correlated with flocculation behavior.It was observed that the particle hydrophobicity and pH were most important since dodecylamine chloride reactions are Ph and concentration dependent

Utilisation of Mineral Slimes and Industrial Waste by Electro Flotation and Selective Flocculation.

Electroflotation and selective flocculation or the combination of both appear to be potential techniques for the beneficiation of low grade mineral slimes and fines generated during mining, milling and other metallurgical operations. Considering the hydrodynamics of flotation process, electroflotation was proved to be an effective and viable technique to separate organic suspending particulate matter generated from leather, textile, metallurgical, oil refinery and food processing plants. Electroflotation is advantageous to process sulphide minerals and minerals that undergo surface changes when exposed to electrolytic oxygen and hydrogen. Adsorption of oxygen, liberated from the anode leads to the formation of elemental sulphur on the surface of the particles. Elemental sulphur thus formed under controlled oxidation enhances the hydrophobicity. Continuous liberation of H+ and OH- leads to drastic changes in the pH of the pulp. Hence, electroflotation technique is more disadvantageous where pH is a critical parameter. Also part of the collector will be either destroyed or dissociated under the influence of pH, electrolytic bubbles and oxidation-reduction environment changes. Selective flocculation of minerals using polymers followed by anyone of the separation techniques such as, flotation, elutriation, filtration, etc. offers considerable promise for processing non-precious oxide minerals. Natural and synthetic high molecular weight polymers have been successfully used as flocculants. Lack of desired specificity is the major set back in this process. However, specificity can be introduced by incorporating active groups in the polymers. Though there is enough literature on selective flocculation of synthetic mineral mixtures, reports on the flocculation of multi-component natural ores are scant. Further, it is generally observed that the prediction of selective flocculation on the basis of results obtained from single mineral tests fairly agrees with synthetic mineral mixtures but rarely on natural systems

The Surface Properties of Aqueous Fluorapatite & Maghemite with Reference to the Dephorization of Magnetite

The Luossavaara-Kirunavaara AB(LKAB) in northern Sweden is one of the biggest suppliers in the world of high grade iron ore products. However, the Kiruna magnetite ore deposit contains an average of 1 wt% phosphorus (mainly fluorapatite), which is detrimental to the blast-furnace technology and the quality of the iron products. Conseque-ntly the apatite content has to be minimized. After magne-tic separation the dephosphorization is performed by froth flotation of the apatite from magnetite fines using a fatty acid type collector (ATRAC)in a combination with sodium silicate. The concentrated magnetite fines are then treated in a pelletizing plant

Research at the interface between industrial needs and scientific demands

Godkänd; 2004; 20061210 (ysko

Betydelsen av grundläggande forskning för mineraltekniska processer

Godkänd; 2006; 20070122 (ysko)</p