Waste Processing

Bauxite residue (red mud) with a high alumina content requires large amounts of fluxes during smelting, which increases the overall process cost, the energy consumption during smelting, and the acid consumption during slag leaching and decreases the throughput of bauxite residue in the smelting phase. Therefore, alumina was removed (or recovered) from bauxite residue by alkali roasting prior to smelting. The sample after alumina removal could be smelted at 1500°C without the need of adding any flux to obtain a clear slag-metal separation. After smelting, the slag was leached with acids (HCl, H 2 SO 4 , or HNO 3). The recovery yields of the rare-earth elements (REEs), except scandium, drastically decreased in the low-alumina slags, compared to the original bauxite residue. These poorer recovery yields are due to the formation of a perovskite (CaTiO 3) phase, which binds REEs except scandium. CaTiO 3 is a stable phase and does not dissolve in acids under normal conditions. Therefore, slag was quenched to suppress the CaTiO 3 formation. The REEs and titanium could also be dissolved in acidic solutions at 25°C by quenching the molten slag. Removal of alumina from bauxite residue by alkali roasting with sodium carbonate requires high temperatures ([900°C). Therefore, sodium carbonate was replaced with sodium hydroxide to decrease the energy consumption by decreasing the roasting temperature (\500°C).

This paper presents the methodology for design and fabrication of human waste disposal system for Indian railway with the related search. The study specifies factors influencing the human waste disposal and recommends a number of design options for human waste disposal system for Indian railway. These are based on a systematic study of the human waste disposal system and testing of a prototype model of it. For which we consider literatures reviews & some of them are explained.

The main goal of the study performed in this paper is the improvement of disposal
and processing of technogenic wastes with high nonferrous metals content. In
particular, the peculiarities of the copper recovery process from technogenic raw
materials by using a hydrocarbonylation method are considered. A substantiation of
the real possibility of selective copper recovery from polycomponent solutions,
formed as a result of technogenic raw materials repulping or leaching, is adduced. At
that, the primary reagent is carbon monoxide and the duration of the process cycle is
not to exceed 10 hours at low specific power consumption and the high purity of
product copper.

The authors have proposed their own newly developed universal procedure for assessing waste and selecting methods of processing the waste for agricultural purposes. Increasingly more rigorous environmental legal regulations, especially pertaining to sustainability in agricultural and chemical production, were the most convincing motivation for such approach. The procedure is based on technological and environmental safety criteria. Special attention is devoted to the chemical processing of hazardous wastes into fertilizer products and the underlying reasons for such methodology. As opposed to physical and biochemical processes, in chemical processes the agents used completely change the chemical structure of the waste materials or at least that of some of their components. As a result, new phases are formed and the harmful properties of the initial material are eliminated. Prospects for the chemical processing of hazardous wastes are demonstrated using as an example the utilization ...