Research Smoke Arsenic Treatment Methods Lead Metallurgical Process

Arsenic is widespread in nature, and rarely in elemental state, arsenic is harmful trace elements, most of the arsenic compounds have strong toxicity, the toxicity of different valence are also different. Arsenic (Ⅲ) compounds is more toxic than arsenic (V). Most arsenic in the environment is presence of inorganic arsenic. At present, the main processing method for arsenic materials are acid leaching, alkaline leaching, salt leaching, etc.And the main for treatment of wastewater containing arsenic includes chemical precipitation, adsorption, ion exchange method, biological arsenic removal method, etc. The most important one of which is the chemical precipitation method, which in eludes the removal of arsenic salt precipitation, arsenic removal of aluminum salt precipitation, calcium salt of sodium arsenic removal, arsenic removal, control of the pH value, can achieve good effect in removing arsenic.In this study, three kinds of methods for leaching lead smelting dust was compared which included water leaching, acid leaching and alkaline leaching, the effects of pH, leaching agent concentration, liquid-solid ratio, leaching time and leaching temperature on the rate of arsenic leaching were studied, eventually established the inexpensive and readily available water as leaching agent toleaching process route of high arsenic dust lead smelting process, the optimal process route and process parameters were determined as the ratio of liquid to solid=15:1, pH=2.5, temperature90℃and time was120min. The leaching kinetics of arsenic from lead smelting high arsenic dust was simulated using the Johnson-Mehl-Avrami (JMA) model for the reaction between liquid and solid. The influences of temperature on the reaction rate of arsenic were investigated. Kinetics studies indicate that the diffusion control was the rate limiting step in the leaching process of arsenic within the selected temperature range, the kinetic equation is-ln(1-a)=9.4×106e-50380/RT t0.3106with the leaching process frequency factor of9.4×106s-1and the apparent activation energy of50.38kJ/mol.Using the response surface method optimization experiments for leaching process. The effect of important parameters, such as Liquid-solid ratio, Temperature and Time, was investigated and the process comditions were optimized using response surface methodology(RSM) based on central composite design(CCD). The results show that the effect of temperature on the manganese leaching yield is the most significant, the effect of Time is second, and the effect of is Liquid-solid ratio minimum. Through the response surface analysis of the optimum leaching process are as follows:the Liquid-solid ratio=14:1, Temperature85℃, time120min. Under the optimized conditions,the arsenic leaching yield is89.88%. After the second water leaching,the total arsenic leaching rate of98.1%.Using the pre-oxidation-iron method of removing arsenic to study the smelting lead dust leachate. The results show that in the first arsenic removal, for oxidation the leaching solution with oxidant at first, when pH=4-5, the iron-arsenic ratio=l,30min,30℃, FeCl3is used to precipitation, the leaching rate of arsenic reached99.9%. In the second arsenic removal, control iron-arsenic ratio=10, pH=8, the removal of arsenic solution can well meet requirements of industrial emissions.Through the study on mechanism of leaching the lead smelting high arsenic dust and sink arsenic,showed that the feasibility of using water leaching and salt precipitation of arsenic on arsenic treatment, has the important guiding sense for smeltingof high arsenic dust, and can provide a theoretical reference for the harmless treatment of other high arsenic material.