During the heap leaching, some components of the ore are transferred to the dissolution process of the solution, so that there is a fouling component in the solution. This is only a prerequisite for scaling, and there must be fouling environment-external conditions to produce fouling. The external conditions affecting the heap leaching are evaporation, closed circulation of the solution, pH of the medium, solution flow rate, temperature, pressure, and the like. First, evaporation Evaporation is the main additive factor for fouling in heap leaching. Although the heap immersion is not heated, due to the large surface area of ​​the immersion heap, the leaching period is long, a large amount of water is evaporated, the volume of the solution is reduced, and the ion concentration of the insoluble electrolyte in the solution is increased, causing the solution to be in a supersaturated state, resulting in scale formation. The batching is intermittent spraying. During the intermittent time, the evaporation amount is large, and the moisture on the surface of the heap is always evaporated, and it is in a dry state, and the soluble salts in the solution will also crystallize. A large amount of FeSO 4 ·7H 2 O found on the surface of the heap in the acid heap leaching is formed by the large amount of Na 2 CO 3 found on the surface of the heap in the alkaline heap leaching. The amount of evaporation depends on the time and place. For example, from July to August in Xinjiang, the amount of evaporation accounts for 28.5% of the amount of leachate. From October to November, the amount of evaporation drops to 5%. The higher the temperature, the larger the wind speed and the greater the evaporation; the greater the humidity, the smaller the evaporation. Second, the closed loop of the immersion liquid Most heap leaching adopts closed-circuit circulation of the solution, and the total water consumption of the heap leaching is small, so that some components dissolved in the solution accumulate continuously, the ion concentration gradually increases, and the total dissolved solids in the final leaching solution exceeds the stirring leaching liquid several times. Even dozens of times. For example, the cotton pit ore contains some fluorite , which is also leached with sulfuric acid, and the acidity of the sulfuric acid used in the heap leaching is only 5% of the stirring leaching. The calcium sulphate scaling does not occur in the stirring leaching, and the calcium sulphate scaling in the heap leaching is very serious. Third, the pH of the medium In some cases, the pH of the medium has a great influence on the fouling of the heap leaching. For example, in the acidic solution, many ions such as Fe 3 + , Al 3 + and U 6 + will hydrolyze and precipitate with the pH of the medium; In an alkaline solution, the pH rises, resulting in the conversion of HCO 3 - to CO 3 2 - , and if Ca 2 + is present in the solution, CaCO 3 precipitation occurs. Filter Element,Dust Filter Element,Fuel Filter Element Xinxiang Xin Ming De Machinery Co., Ltd. , https://www.xmdsieve.com
October 31, 2021