A low-gradeantimony deposit originating from district Qilla Abdullah, Balochistan Province of Pakistan, containing stibnite as an economical mineral was beneficiated by froth flotation technique. Flotation parameters such as particle size of the feed, pulp density, pH of the pulp, agitation speed, type and dose of reagents (i.e. collector, frother, activator, regulator and modifier) and the conditioning time were studied on the basis of single-factor variation experiment in order to get the optimum grade and recovery. Regrinding of the rougher concentrate followed by cleaning andrecleaning of rougher concentrateensured a final concentrate grade of 65.12% Sb@ 85.79% recovery. This concentrate is suitable for the extraction of metal and production of chemicals. Materials and methodsA representative sample of the ore, consisted of lumps of various sizes, was obtained from Qilla Viala area of Qilla Abdullah district of Balochistan. It was jaw crushed to a size of 20-25 mm followed by roll crusher to product of 5-6 mm. A head sample for chemical analysis was obtained by coning-quartering and riffling of the crushed ore while the remaining ore was used for processing studies.The representative sample of ore was ground to pass 200 mesh sieve with the help of disc pulverizer (Denver, USA) and its chemical analysis was performed by gravimetric, volumetric and instrumental methods. Silica, alumina, lead, barium and sulphur were determined gravimetrically, while antimony by iodometric titration, iron by oxidation reduction titration, calcium and magnesium by complexometric titration. Sodium and potassium were estimated by flame photometer (PFP7, Jenway Limited, England). The chemical analysis of head sample and final concentrate is given in Table I & IV respectively. Flotation experiments were conducted in a flotation machine (Model: D-12, Denver, USA), using stainless steel cells of 1& 2 litres capacity. The ore was ground from 70-99% passing 200 mesh (74µm) to study the effect of particle size. Flotation feeds were prepared by wet grinding of roll crusher product in rod mill (Denver, USA) with solid to liquid ratio of 1:1. The effect of pulp density during conditioning was studied by varying the percentage of solids from 20-35%. Similarly the effect of pH was studied by varying it from 8.0 to 9.5 with soda ash. Impeller speed was varied from 900-1200 rpm to study the effect of agitation. Lead acetate was employed to activate stibnite mineral and its amount was varied from 500-1500g/t. Sodium silicate was added to depress the silicate gangue minerals and its quantity was increased from 200-1000 g/t. Sodium cyanide was applied to depress associated pyrite gangue in cleaning stage and its amount was varied between 100 and 500 g/t. Potassium amyl Table III. The flow-sheet developed from locked cycle tests for preparing high-grade antimony concentrate is given in Fig.10. Results and discussionIt is evident from the chemical analysis presented in Table-1 that 20.04% head grade of antimony is sufficient to exploit the...

IntroductionTungsten is a whitish-gray metal with many unique properties and a wide variety of uses. Its largest use is as tungsten carbide in cemented carbides. Cemented carbides (also called hard metals) are wear-resistant materials used by the metalworking, mining and contraction industries. Tungsten metal wires, electrodes and contacts are used in lighting, electronic, electrical, heating and welding applications. It is also used to make heavy metal alloys for arnaments, heat sinks and high-density applications, such as weights and counterweights, super alloys for turbine blades, tool steels, and wear-resistant alloy parts and coatings. Tungsten composites are used as a substitute for lead in bullets and shot. Chemical uses of tungsten include catalysts, inorganic pigments and high-temperature lubricants (Shedd, 2001).The main ores of tungsten are (a) wolframite [(Fe, Mn) WO 4 ] having a specific gravity of 7.1-7.9 and it is feebly magnetic and (b) scheelite (CaWO 4 ) having a specific gravity of 5.9-6.1. Scheelite is often closely associated with quartz, with which it is easily confused because of the very similar physical appearance of these two minerals. Fortunately, scheelite always fluoresces a characteristic electric blue to yellow color when irradiated with ultraviolet light, which greatly facilitates both prospecting for scheelite and the evaluation of scheelite deposits (Blackburn, 1988).Tungsten metal has high strategic importance. High prices and ready market for acceptable tungsten concentrates present very attractive incentive for the mining and processing of tungsten ores. Since all tungsten ores are very friable and slime easily, concentration must take place as soon as the mineral has been liberated by either crushing or grinding methods.Regardless of the care taken in the selection of the route of beneficiation, a certain portion of the tungsten is going to be slimed, both during the mining and the milling process. In general the ability to recover the slime tungsten means the difference between success or failure of the milling installation and of the preceding mining operations.The dominating processes for concentration of tungsten ores are gravity concentration and froth flotation methods. The beneficiation process used is dependent upon the type of ore. Experts like Michell and Gisler have excellent review articles on the processing of tungsten ores (Weiss, 1985). In gravity treatment, care should be taken to concentrate the value and the coarsest possible size avoiding over-grinding. Jigs, tables, rag frames, and spirals are commonly used. In original flotation practice, tungsten ores are beneficiated by using a carboxyl collector and sodium silicate as a depressant. Tannin is used as a depressant in case of associated calcite, fluorite, dolomite and apatite. However, it is quite difficult to obtain economic grade as scheelite itself is readily depressed. Many scheelite flotation mills attempted to make a 60% WO 3 concentrate by gravity means or by tabling of the flotation concentrate...