At present, the automatic control links of the coal preparation plant mainly include the gravity sorting process (especially the heavy medium sorting process), the flotation process, the tailing mud water sedimentation and concentration automatic dosing, and the TBS sorting process in the coarse coal slime treatment.
Flotation
As the primary flotation method sorting metal ore and non-metallic mineral beneficiation, also is widely used in fine coal separation. Coal slurry flotation is a complex physical and chemical process. The main factors affecting the flotation effect are the characteristics of feed slime, slurry concentration, pharmaceutical system, aeration, liquid level and flotation process. The stable and reliable flotation control system can improve the yield of flotation clean coal, stably control the ash level of clean coal, reduce the consumption of chemicals, and improve the filtration and dewatering effect of clean coal. The automatic control of flotation mainly includes the detection of material properties, the adjustment of feed concentration, the addition of chemicals and the monitoring operation.
The inspection of the incoming material properties mainly includes the feed concentration and flow rate detection. The feed concentration can be measured by an isotope concentration meter or a double capsule concentration meter. Isotope concentration meter requires strict protection, but the scope of application is large, non-contact type, easy to install, high measurement accuracy; double membrane box concentration meter does not have protection problems, more suitable for concentrated flotation, small measurement error; but low concentration In the direct flotation process, the concentration measurement error is large. The use of electromagnetic flowmeters for the detection of flotation feed flow is relatively small, and the use of ultrasonic flowmeters is relatively small.
The feed concentration control is achieved by adding dilution water. The concentration adjustment process is as follows: the flow rate and concentration signals of the raw coal slurry and filtrate are measured by electromagnetic flowmeter and concentration meter respectively, and the amount of dry coal slurry and the amount of circulating dry coal mud are obtained by multiplication, and the sum of the two is flotation The total amount of dry coal in the link. On this basis, according to the floating concentration required by the flotation process, the flow rate of the suspended coal slurry under this condition is calculated. By subtracting the amount of the pulverized coal slurry and the filtrate, the flow rate of the desired dilution water can be obtained. After the flow and concentration signals in the above process are analyzed by the instrument acquisition and PID calculation processing, the control commands are transmitted to the electronically controlled hydraulic actuator through the output module, and the valve is actuated.
The control of the amount of flotation agent added is based on the detection of the amount of the slurry and the calculation of the amount of the drug, and the metering pump is used to realize the automatic addition of the agent. The automatic control process is as follows: on the basis of analyzing the properties of the suspended coal slurry, the coal preparation plant determines the relationship between the amount of the chemical agent and the concentration of the suspended coal slurry and the amount of dry coal slurry through the flotation test under the premise of satisfying the quality of the clean coal product. And establish the corresponding mathematical model. In the process of chemical regulation and control, on the basis of measuring the concentration of coal slurry and the amount of suspended coal, the mathematical model function transformation is used to determine the given value of the flotation agent under the premise of satisfying the quality of clean coal products. By comparing with the actually measured dosing feedback signal, the PID operation is processed and a signal command is output to control the action of the dosing solenoid valve.
In addition, the control of the liquid level and aeration volume of the flotation machine also has certain application. However, since the liquid level meter and the aeration amount are not adjusted frequently in actual operation, it is not sensitive to the influence of the product quality, so most coal preparation plants still adopt Manual adjustment.
The flotation process of Huaibei Coal Preparation Plant adopts a combination of feedforward control and feedback control to regulate the operation of the flotation system. The feedforward control adjusts the dosage of the chemical on the basis of tracking the dry coal content in the flotation feed; the feedback control further adjusts the pharmaceutical system by optimizing the control algorithm based on the monitoring of the clean coal ash. The production results show that under the premise of ensuring the clean coal ash, the flotation control system combined with feedforward and feedback control improves the yield of clean coal and reduces the consumption of chemicals.
Introduction of Screw Conveyor
Screw conveyors, also known as auger conveyor,Spiral Conveyor, are made for simple conveying duties applications. The real strength of our company, however, is our ability to produce individually designed units that include features to overcome awkward installations, materials that are difficult to handle, or include performance or process functions beyond simple conveying. Some requirements may be concerned with aspects of hygiene, others with bulk solids that have poor or delicate conveying properties.
Screw conveyor is divided in two types rigid screw conveyor and shaftless screw conveyor.
Rigid screw conveyor is suitable for non-sticky powder and small particle material such as cement, fly ash, lime, flour, starch, food additive etc.
Shaftless screw conveyor is suitable for sticky and easy winding materials such as sludge, biomass.
Features of screw conveyor
*Tube type and U shape type available
*It can be designed inclined conveying,horizontal conveying and vertical conveying.
*Widely used for all kinds of powder,particles,small block and loose material.
*not suitable for conveying perishable material,high viscosity,less pressure resistant material.
*not suitable for agglomerate or high temperature material.
*not suitable for great corrosive special material and fragile material.
Warranty
Our machines have an automatic 12 months guarantee against faulty material and workmanship valid from the date of dispatch in China or date of arrival at foreign border.
If any problem of the machine under instruction within one year,we are responsible for replacement incuding delivery fee and maintenance.
Lifelong service is offered with cost charge after one year.
Screw Conveyor
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