Research On Purification Of Activated Clay With Inclined Plate Settler

Aactivated clay is the product of bentonite modified by inorganic acid, which has greater adsorption and activity compared with bentonite and is widely applied to petroleum industry, chemical industry, metallurgy, food industry, etc. While the activated clay quality cannot be guaranteed because the montmorillonite content of bentonite mines declines with the developing time being, In order to ensure the high quality of activated clay, the low grade bentonite should be purified. In this paper, the purification method with inclined plate settler for activated clay was introduced to improve the quality of activated clay. Firstly, the design and installation of the inclined plate settler were studied. Secondly, in order to determine the suitability of structure of the homemade inclined plate settler, the resident time distribution was measured with pulse tracing technique using water as the working medium and potassium permanganate as the tracer.And then, the influence of the feed mass fraction and flow rate on the products were also investigated to determine the purification operating parameters. The results were showed below.(1). The homemade inclined plate settler was made by modifying the traditional groove. It was featured with simple structure, low cost, easy to operate and high production efficiency.(2). As the feed flow rate increased, the resident time distribution (RTD) would become narrow and its digital characteristics would become less. Besides, the dimensionless variance was very close to zero thus the flow pattern in this equipment was neither plug flow nor complete mixing flow, but extremely close to the plug flow. Therefore, the structure of the inclined settler was suitable for the purification of activated clay.(3). The influence of the feed concentration and the flow rate on the purification was showed below. The recovery of products and the production efficiency would decline when the feed concentration and flow rate decreased; The granularity and sand content would increase when they were increased, but the decreasing decolourization ratio of products would lead to its poor quality. While, at the same time, its recovery was high and the resident time distribution (RTD) was very close to that of plug flow. As for the feed flow rate, if it was too low, the RTD would not be satisfactory. But if the feed flow rate was too high, the insufficient resident time would bring a negative effect, it would be difficult to remove the larger impurities in the purification experiment and the quality of product would be poor.The experiment data showed that, as for the products, compared with the original activated clay, the sand content would decrease to 4%, the decolourization ratio would increase to 76%, the average diameter would resize to 27μm and the recovery of activated clay would increase to 77.5% when purified as the feed mass concentration was 10% and the feed flow rate was 2.0t/hm2. Therefore, the quality of activated clay was improved after being purified by the homemade inclined plate settler with lower sand content, less average diameter and higher decolourization ratio.(4). By adopting a subsidence purification equipment in the traditional activated clay production process and avoiding the complicated material purification operation, the method not only simplified the purification process but also made full use of the low grade bentonite to produce activated clay.(5). Compared with the traditional purification of bentonite, purifying activated clay solved the problem of dehydration and had the advantages of high production efficiency and recyclable usage of waste acid.