The experiment study of using industrial waste red mud to manufacture foamed blocks
Red mud foamed block is prepared using waste of aluminum oxide production—red mud, soft burning magnesium powder (MgO), bischofite (MgCl<inf>2</inf>·6H<inf>2</inf>O) and various addition agents. The influence of each factor on strength and density of red mud foamed block is analyzed by orthogonal experiment in this paper. The best ratio is obtained as follows: red mud 30%, MgO 40%, F-3 high efficiency composite foaming liquid 3.0 kg, MgCl<inf>2</inf>·6H<inf>2</inf>O 20% and fine sand 5% (all dry ingredients about 700 kg).
Applications of bauxite residue: A mini-review
Bauxite residue is the waste generated during alumina production by Bayer’s process. The amount of bauxite residue (40–50 wt%) generated depends on the quality of bauxite ore used for the processing. High alkalinity and high caustic content in bauxite residue causes environmental risk for fertile soil and ground water contamination. The caustic (NaOH) content in bauxite residue leads to human health risks, like dermal problems and irritation to eyes. Moreover, disposal of bauxite residue requires a large area; such problems can only be minimised by utilising bauxite residue effectively. For two decades, bauxite residue has been used as a binder in cement industries and filler/reinforcement for composite materials in the automobile industry. Valuable metals and oxides, like alumina (Al2O3), titanium oxide (TiO2) and iron oxide Fe2O3, were extracted from bauxite residue to reduce waste. Bauxite residue was utilised in construction and structure industries to make geopolymers. It was also used in the making of glass-ceramics and a coating material. Recently bauxite residue has been utilised to extract rare earth elements like scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), neodymium (Nd) and dysprosium (Dy). In this review article, the mineralogical characteristics of bauxite residue are summarised and current progresses on utilisation of bauxite residue in different fields of science and engineering are presented in detail.
Investigations on the surface roughness produced by ball burnishing
Abstract Burnishing, a plastic deformation process, can be used to finish surfaces. Experimental work was conducted on a vertical machining centre to establish the effects of various ball burnishing parameters: depth of penetration, feed, ball material, burnishing speed and lubricant, on the surface roughness of AISI 1045 specimens. The ball materials used were WC and SUJ2. It was found that all the parameters studied affect the surface finish to varying degrees. The surface roughness parameter Rtm first decreases and then increases with increasing depth of penetration. The effects of feed and burnishing forces on the surface finish also showed similar trends. The effect of speed depends on the type of lubricant used. Grease is a better lubricant than cutting oil for the speed range of 450 mm min−1 to 1200 mm min−1. With appropriate selection of the process parameters, a pre-machined surface roughness of about 4 μm can be finished to approximately 0.7 μm.