Removal of cyanide from alumina smelter wastewater using precipitation and filtration technique

Aluminum is a metal that is used in many products because of its good conducting properties. However, in the production process, aluminum is not obtained easily but through a long process. In aluminum smelting process, wastewater that is produced indicates the existence of pollutants as determined by several indicators of water pollution, one of which is cyanide that will threaten human and environmental health if not treated properly. This study was conducted to determine the optimal dose of ferrous sulfate to remove cyanide, the precipitation and filtration process efficiency in reducing cyanide, and its effect on pH of wastewater. Data were collected from an aluminum smelting company, and experiments were conducted in the laboratory. Based on results, ferrous sulfate dose of 93 mg/l is the most optimal dose in removing cyanide with an efficiency of 58.74±0.51%, while filtration process provides an efficiency of 81.65±0.42%. Precipitation with ferrous sulfate makes pH value of wastewater decrease, but filtration process increases the value again. Throughout the whole process, cyanide can be reduced by a combination of precipitation and filtration process with the efficiency of 92.43±0.26% and an average final effluent concentration of 0.78 mg/L from an initial concentration of 10.3 mg/L.

Stereolithographic Additive Manufacturing of Zirconia Electrodes with Dendritic Patterns for Aluminum Smelting

Zirconia electrodes with dendritic patterns were fabricated by stereolithographic additive manufacturing (STL-AM). A solid electrolyte of yttria-stabilized zirconia (YSZ) was selected for oxygen separation in the molten salt electrolysis of aluminum smelting without carbon dioxide excretion. Thereafter, 4, 6, 8 and 12-coordinated dendritic structures composed of cylindrical lattices were designed as computer graphics. The specific surface area of each structure was maximized by changing the aspect ratio. The spatial profile and surface pressure of the hot liquid propagation in the dendrite patterns were systematically visualized by computational fluid dynamics (CFD). During the fabrication process, a photosensitive resin containing zirconia particles was spread on a substrate, and an ultraviolet (UV) laser beam was scanned to create a two-dimensional (2D) cross-section. Through layer laminations, three-dimensional (3D) objects with dendritic structures were successfully fabricated. The ceramics were obtained through dewaxing and sintering.

Co-disposal Research of Red Mud and Aluminum Electrolysis Solid Waste Based on External Thermal Reduction and Smelting Separation

In large aluminum smelting enterprises, the solid wastes of red mud and waste cathodes are satisfied the basic elements requirements of the solid-solid direct reduction technology. Thus, it is proposed a solution to use waste cathodes and red mud under indirect heating supply to produce pellets and to utilize in situ. It has been studied the reduction mechanism of red mud and waste cathode, the influence of carbon allocation method on pellet reduction and the research of the smelting separation and product quality. Experiment shows that the iron of red mud can be successfully reduced by waste cathode and anode toner at high temperature. The metallization rate of iron in red mud can reach more than 95% and the quality of pellets is more suitable with the mode of external carbon mixing. In order to carry out effective melting and separation of slag and iron, the red mud pellets must to be briquetted or to reserve a molten pool before charging into the melting furnace. After separation, the content of iron and carbon in steel can reach about 98.85% and 0.13% respectively, and the yield of iron elements can reach more than 96%, the harmful components flow into the slag can be effectively solidified. Content of alumina in the slag reached about 37% which can be economically recycled to the alumina purification process as a matching.

Aluminum Slag Separation Process Analysis Through a Vibratory Machine in the Foundry Process

A The aluminum smelting industry has some challenges, due to the characteristics of the alloy that cause reactions that should be controlled. During the foundry process, the alloy is oxidized by contact of the molten aluminum with the ambient air. Oxide films forming on the surface of the molten metal must be removed during the cleaning of the furnaces in order to avoid contamination of the alloy to be used in the production of parts. Analyzing the melting process of a metallurgy at the industrial complex in Manaus, we saw that during the cleaning of the furnaces a metal tool is used to remove the slag, which brings with it a high level of aluminum brought about by the mechanical drag of the tool. As the company in question does not have resources to recover the metal aluminum contained in the slag, it is destined for the other institution which carried out the processing through the process of refusion of the slag and extraction of aluminum. The high level of losses in the process due to the discarding of slag generates considerable financial damage to the institution, reflected directly in the cost of manufacturing the products. In this way, the aim of the present work was to develop equipment for the extraction of the metal aluminum contained in the slag and consequently to reduce the losses in the process. The design of the equipment was chosen through a product development methodology, which made it possible to define the design specification, which can count on a container for the receipt and separation of the slag by means of the vibration brought on by motorvibrators installed at its ends, followed by a slingshot drawer responsible for the storage of the metal after the solidification and support/translate cars of the containers.

The Study of Carbon Recovery from Electrolysis Aluminum Carbon Dust by Froth Flotation

A large amount of carbon dust is generated in the process of aluminum smelting by molten salt electrolysis. The carbon dust is solid hazardous waste but contains a large quantity of recyclable components such as carbon and fluoride. How to recycle carbon dust more effectively is a challenge in the aluminum electrolysis field. In this study, X-ray diffraction, scanning electron microscope, and other methods were used to analyze the phase composition of electrolytic aluminum carbon dust. The effects of particle size distribution of carbon dust, impeller speed, reagent addition, mixing time, and flotation time on the flotation recovery of carbon dust were studied. The optimal flotation conditions were obtained and the flotation products were analyzed. The results show that the optimal particle size distribution is 70% of particles below 200 mesh, corresponding to a grinding time of 11 min. The optimum speed of the flotation machine was to be between 1600 and 1800 r/min with the best slurry concentration of 20–30% and 5 min mixing time, and the collector kerosene was suitable for adding in batches. Under the above conditions, the recovered carbon powder with a carbon content of 75.6% was obtained, and the carbon recovery rate was 86.9%.

Utilization of bus tree wood (Melaleuca sp) as environmentally friendly fuel for household industrial scale Aluminum smelting stoves in Merauke, Papua

The purpose of this study is the use of bus wood trees as fuel for aluminum smelting for the home industry because it has a good heating value and is very efficient, from the laboratory test results, the bus tree wood has a calorific value of 5981 (calories/g). The methods used experimental and analytical to get the results from the use of bus wood as fuel for aluminum smelting which will certainly produce good mechanical properties. The results obtained a good combustion process that releasing all the heat contained in a fuel and done with three combustion control processes, including a fairly high temperature to ignite and maintain the flame of the fuel, turbulence or mixing O2 and the use of good fuel and sufficient time to complete combustion process. The fuel (bus wood) which is inputted in the furnace is designed so that the combustion process takes place more completely with minimal heat losses. The results of temperature changes seem a thermocouple and crucible furnace insulator material were very good heat resistance hence the time of the melting process it doesn't take longer which is 15 minutes. The aluminum in crucibles has melted at a temperature of 723℃.

Acute and Chronic Effects of Aluminum Smelter Dust on Hematology, Metal Bioaccumulation and Oxidant-antioxidant Status in Rat

Background: Aluminum smelting industry is implicated with documented health risks. This study examined toxic effects of aluminum smelting dust as a real-life chemical hazard instead of single aluminum compounds, which seldom exist in real life. Methods: Adult male rats were gavaged acute (3 consecutive days) and chronic (6 weeks) doses of two dust concentrations (10 and 20 mg kg-1). Experimental investigation included toxic metal accumulation and biochemical analysis of blood and liver. Result: Aluminum and iron were highest in dust and respectively accumulated in brain, liver and kidneys. Anemia, inflammation, liver and kidney damage and oxidative stress were established in view of thrombocytopenia (35%), leukocytosis (41%), lymphocytosis (55%) and alterations in aminotransferases, creatinine, malondialdehyde, superoxide dismutase and catalase. Aluminum facilitation of iron-mediated lipid peroxidation is suggested. These findings drew attention to the magnitude (dose-dependent) and persistence (time-dependent) of aluminum dust as health compromising and are of particular significance to workers in aluminum smelting industries.