Among the wide variety of modern surface chemistry analytical techniques, contact angle measurements still remain attractive for wetting characterization of solid surfaces. It is demonstrated that the contact angle value depends on the technique used when nonideal, heterogeneous and rough, solid surfaces are examined. Reagents and Materials Three different solid surfaces were used in the … Read more
The cementation of gold on to copper and zinc in ammoniacal solutions has been investigated using electrochemical techniques and conventional cementation experiments: Studies of cathodic reduction of Au(NH3)2+ have shown that the cathodic reaction can be expressed as: Au(NH3)2+ + e = Au + 2NH3 and the standard reduction potential, E°, has been estimated to … Read more
Drying System Design The fluid bed dryer has been designed for the specific requirements of drying a 6 mm x 0 (¼” x 0) feedstock of anthracite culm and occasional intermittent feeds of anthracite silt. The feed moisutre of the culm ranges between 16 and 18 per cent by weight and is approximately 24 per … Read more
Recent research into the mechanisms of crushing processes has led to the establishment of new criteria for the effective design and operation of comminution plants. This paper reviews this work and gives examples of the productivity gains and cost benefits that have been achieved in the practical application of these findings. Large cost reductions have … Read more
Mechanical Development – Laboratory Testwork Derrick Manufacturing Corporation originally developed the 1.22m x 2.44m Flo-line screen for rock chip removal from drilling muds. It features a 3° reverse angle deck slope and is powered by dual 1.1 kW TENV motors rotating in opposite directions. Figure 1. Screen feed enters from the lower end and, due … Read more
The Nature of Activated Carbon “Activated carbon” or “activated charcoal” is a generic term applied to amorphous carbon materials that have adsorptive capability. These materials are made from different sources and are available as powder, pellets, or grains. Their common characteristic is a very large surface area in the range of 600 to 1200 m²/g … Read more
Heavy media separation is one of a number of pre-concentration techniques for coarse feed which, when the ore is amenable, offers economic advantages in the mining stage and/or the processing stage. In mining, simpler and cheaper methods may be used if a greater proportion of waste material can be included in the mining blocks that … Read more
Leaching Chemistry of Gold Silver and Manganese Thiourea is a reducing and complexing agent and can be used for the processing of gold and silver. The redox potential of gold(I) and silver(I) thiourea complexes in acidic thiourea solutions are 0.380 and 0.023 V (vs SHE), respectively (Kazakov et al., 1983; Lodeishchikov et al., 1975). Thiourea, … Read more
Metal Removal Processes of Wetlands A wetland environment can remove metals from influent waters in a variety of ways. As chemical oxidation takes place, oxides and hydroxides of iron can be expected to precipitate from surface flow, resulting in the characteristic yellow sediment in mine drainage known as “yellow boy”. These precipitates coat the surfaces … Read more
Selective beneficiation of fine particles depends heavily upon the flotation separation process. Conventional froth flotation for many ore systems is very effective for particles between 300 and 20 µm in size, but the flotation efficiency commonly drops off as the particle size decreases below 20 µm. Flotation kinetics has been used by Sutherland (1955) and … Read more