Efficient thickeners are available in a variety of models with specifications equivalent to metric diameters of 6.9 and 12 m. Figure 7 shows one of the different types of high efficiency thickeners. The high-efficiency thickener is characterized in that the pulp is degassed by the degassing tank and then supplied to the manned mixing column, where it is uniformly mixed with the flocculating agent, and then diffused from the diffusing plate at the lower end of the column to the four sides to be fed into the slime layer. It prevents air bubbles in the slurry. The mud layer is agitated, and the supplied slurry does not impact the slime layer to destroy the sediment. At this point, the floc that has flocculated into a cluster precipitates downward and is discharged by the squat arm into the discharge opening; the unflocculated fine-grained slime and liquid are “filtered†by the slime layer when the upper layer of the slime layer is loose. After agglutination, the liquid rises to the supernatant. Therefore, the interface between the supernatant and the slime layer is clear during the operation, and the mass concentration of the suspended solids does not exceed 200 mg/L. Batch filters are commonly used to treat liquefied cyanide pulps that are difficult to filter because they can wash the filter cake for extended periods of time. However, due to its low production capacity and the use of many equipments, the plant covers a large area and is less used. Personalized Glass Bong,Small Glass Bongs,Small Bong Pipe,Cute Bongs Yangzhou Maishun Glass Products Factory , https://www.maishunglass.com
Thickener products of high water content, gold and cyanide remaining capacity, washing recoveries majority of only 90% to 95%, resulting in the loss of gold cyanide with the pulp. If a sulfur-containing tailings or copper, lead, etc. can be used as a high concentrate for sale, it will be a substantial tail was filtered off and the tailings in transit, caused environmental pollution and economic loss. China's Jinchang, Jiaojia and Guilaizhuang gold mines use a box filter press to filter the thickener discharge, the gold washing rate of 99% or more. The Sanshan Island Mine directly washed the tailings with a filter press. The washing rate was 0.74%, and the washing rate per ton of dry ore was 97.42%. The water content of the filter cake drops to 10%~17%, suitable for dry stacking or transportation.
2) Filtration and Washing Method Filtration and washing is the process of separating the leached pulp by liquid-solid separation by using a filter, that is, using a porous filter cloth as a medium, using a vacuum and applying pressure to form a certain pressure difference on both sides of the medium. This pressure differential draws (or presses away) the liquid from the slurry through the filter cloth. The solid particles (ie, the filter cake) are trapped on the surface of the filter cloth to achieve liquid-solid separation. Filtration washing also rarely uses a single filter. Generally, several filters are connected in series, that is, the filter cake which is leached from the slurry filtered by the first filter is added with washing water in the stirring tank, and is thoroughly stirred (washed) and filtered ( Liquid-solid separation), in order to achieve the purpose of washing, in addition, in addition to the addition of water in the agitation tank, washing water can be sprayed on top of the filter to further wash away the dissolved gold between the solid particles or the surface. This part of the wash water is recovered simultaneously with the filtrate. [next]
When the concentration of cyanide leaching pulp is low (about 30% by volume), in order to increase the productivity of the filter and the efficiency of filtration and cleaning, and further clarify the precious liquid, a first-stage single-layer thickener is often added in front of the filter to To increase the concentration of the ore and buffer the stable amount of minerals, and add a certain amount of polypropylene guanamine flocculant to the thickener, so that the concentration of the filter is more than 55%. At the same time, it can also clarify the effect of leaching the slurry and the whole filtrate, thereby further improving the washing efficiency and reducing the pressure of purifying the noble liquid. Figure 8 is a concentration and two-stage filtration washing process of a cyanide slurry in a cyanide plant in China. The plant uses this process, the total washing recovery rate of gold is 98.27%.
The characteristics of the filtration washing process are: the amount of washing water is small, the washing water of each level can be used as a lean liquid, and the filtrates of various stages can be collectively clarified and recovered. When washing in multi-stage filtration, if the last stage is washed with water, it will be more beneficial to recover dissolved gold and cyanide. Since the amount of washing water in the filtration washing is small, it is advantageous to increase the grade of gold in the precious liquid, and is also advantageous for the precipitation recovery of gold and the treatment of cyanide-containing wastewater. Because the filter cake contains less water, the cyanide tailings are easy to manage and transport. However, the structure of the filter is relatively complicated and needs to be equipped with a vacuum system, so the management and maintenance of the equipment are troublesome, the power consumption is large, the production cost is high, and the operation is complicated.
At present, there are many types of filters for leaching slurry washing, such as an external filter type cylindrical vacuum filter, an internal filter type cylindrical vacuum filter, and a disc type (or vane type) vacuum filter. The horizontal vacuum belt filter is a new type of filtration and washing equipment. This section focuses on the following. [next]
The horizontal vacuum belt filter (see Figure 9) has a horizontal frame-type rigid structure. The trough filter chamber and its 38 rollers reciprocate along the upper rail of the frame. The filter cloth is made of high-strength 3927 polyester synthetic fiber filter cloth, which is used as both filter belt and conveyor belt on the filter; filter, wash, dry and clean the filter cloth for continuous operation. The filter chamber has a plurality of liquid outlets for extracting two phases of gas and liquid, and the vacuum hose is connected with the liquid collection tube. The liquid collecting pipe is connected with the gas-liquid separator, and a vacuum switching valve is arranged thereon, and the filtrate is discharged from the liquid discharging port of the separator. The head wheel can be used for stepless speed regulation, and the circular filter belt is continuously circulated and moved. The filtration, washing and drying sections can be arbitrarily changed according to the production process. The filter cake is peeled off by the scraper at the head wheel; subsequently, a filter cloth is used to clean, adjust, tension and correct the flattening device. Switching the vacuum, returning to the filter disc, tensioning the filter cloth, correcting the deviation, etc. are all automatically completed by the air control.