According to the method of discharging ore, the sedimentation and concentration facilities are divided into two types: intermittent discharge type and continuous discharge type. The former periodically discharges concentrated products, and the latter continuously discharges concentrated products. There are sedimentation tanks, filter tanks, etc. for intermittent discharge type; cone type thick mud buckets, rake thickeners and centrifugal concentrators for continuous discharge type. Mineral processing plant, the dehydration of the general use of fine material Rake Thickener continuous nesting.
The smelting concentrator is currently undergoing large-scale development, and the foreign concentrator has a diameter of 150 to 183 meters. In addition, the traditional structure and process are continuously improved, and the development of high-efficiency equipment is emphasized, such as improving the feeding mode, studying the geometry of the thickener, adding flocculant to improve the concentration efficiency and processing capacity, etc. The high-efficiency concentrator unit appeared in the late 1970s. The production capacity of the area has increased many times compared with the traditional equipment, which is of particular importance for the concentrator that has a large production scale, a tight industrial site and a severe cold weather that must be used indoors.
(1) Structure of the 耙 type thickener
A Concentrator's tank The tank structure of the concentrator can be made of steel, concrete, wood or lining in the soil according to its specifications, feeding properties, operation requirements for removing the grit, and topographical conditions. The groove wall and the groove bottom can be made of the same or different materials (or masonry). To prevent corrosion, the inner wall of the groove can be painted or lined with synthetic rubber or plastic. In the case of good soil, it is also possible to use the stone masonry or the clay raft to make the bottom of the tank without using reinforced concrete.
According to the specific situation, the tank installation method of the concentrator has the following types:
(1) The trough body is placed on the ground, the bottom is embedded below the ground, and an underground corridor is provided for mine discharge. This type of structure facilitates the support of the trough body, and the civil construction cost is low, but the concentrated king machine grit conveying facility is located a few meters below the ground, and the production operation conditions are poor. Large and medium concentrators often use this configuration.
(2) The trough body is placed above the ground and supported by reinforced concrete beams and columns. The sand can be pumped to the next process by self-flow or by sand pumping on the surface. The construction cost of this type of structure is relatively high, but the production and operation conditions are good, and the bottom space can be used for other purposes. Generally, medium and small concentrators or concentrators built indoors sometimes adopt this configuration.
B Concentrate feeding method In the past, the thickeners generally used the center feeding, and the slurry was sent into the feeding cylinder in the center of the thickener, and then slowly flowed into the subsidence zone. In recent years, foreign concentrators have been introduced for peripheral feeding and bottom feeding. The slurry distributor of the peripheral feed concentrator is immersed in the slurry and installed at the periphery of the concentrator with a certain depth from the overflow weir. Compared with the central feedstock, the peripheral feed concentrator has a large processing capacity, and the solid content in the overflow is reduced by about 50%, for example, from 2.72 g/liter to 1.3 g/liter, and the concentration of the underflow product is increased by about 4.2%; The flow of the machine is fed from the central pipe at the bottom of the concentrator, which shortens the falling distance of the particles, so the treatment capacity is large, the overflow is clear, the land occupation is small, the reaction is sensitive, and the treatment granularity range is wide.
C Safety protection device The concentrator is equipped with an overload signal and protection device, which is an important measure to ensure the normal operation of the large concentrator. There are currently three types, namely hydraulic, mechanical and electronically controlled safety devices.
(1) Hydraulic type. The device is programmed with an overload monitoring alarm in the line of the hydraulic motor, and the pressure limit valve controls the torque limit of the upper part of the central axis, and the liquid pressure can be directly measured according to the driving line, so as to start the overload warning signal device and the truss lifting device. And a normal indicator or torque logger. If the overload time is too long, the temperature control switch is activated to prevent the liquid from overheating. At this time, the hydraulic system stops working and the truss stops.
(2) Mechanical type. The device is mounted on the end of the worm shaft of the drive head. When overloaded thickener, the end portion of the worm gear reducer driven shaft, by means of a spring disk rotation gear system for mobile signaling device, when it is transferred to a predetermined position, can be turned on mercury switches, audible and immediately Signal, or shut down the device, simultaneously turn on the power of the lift motor, and automatically lift the file. Manual lifting can also be carried out with the hand lifting wheel to avoid damage to the equipment.
(3) Electronically controlled. The unit uses an overload alarm and can be used alone or in combination with a mechanical alarm system. The control work is based on the motor drive current intensity or voltage signal sensing of the concentrator. In the case of using a hydraulic motor abroad, a hydraulic overload alarm is used and its contact signal is programmed into the hydraulic motor circuit.
D Concentrator's transmission mechanism Because the sedimentation speed of fine-grained materials is slow, in order to reduce the interference of the sedimentation process, the rake-type concentrator's boom speed must be slow, so the transmission reduction ratio is large. Generally, worm gear reduction and three-stage gear reducer can meet the requirements; in order to ensure the safe operation of the concentrator, the transmission mechanism must have safety devices to prevent damage to the machine or motor due to excessive precipitation or excessive feed.
There are several types of transmission mechanisms commonly used in concentrators:
(1) Small center drive concentrator. The arm is mounted on the central shaft and is driven by a worm gear reduction mechanism at the center of the tube bridge with safety signals and manual or electric lifting devices.
(2) Large center drive concentrator. The arm is supported by a central truss, the truss and the transmission mechanism are placed on the central column of the reinforced concrete structure or the steel structure, or the hollow column formed by the reinforced concrete box, using a tapered roller bearing or a hydrostatic oil film bearing, and having The transmission mechanism of the planetary gear system. Among such equipment manufactured abroad, those with diameters below #%% meters are generally equipped with automatic or manual lifting devices. For larger diameters, it is equipped with automatic monitoring and control devices such as automatic lubrication, pressure measurement and load measurement.
(3) Small peripheral drive concentrator. The transmission device is mounted on the trolley at the end of the truss arm truss, and the carriage is driven by the gear reducer to move the trolley on the track. No special safety devices are required. When the load is too large, the wheels slip and the car stops moving forward.
(4) Large peripheral drive concentrator. The drive trolley is equipped with a reducer with a pinion. On the periphery of the concentrating tank, a rack of racks is fixed in parallel with the track. A pinion of the reducer meshes with the rack to push the carriage forward and drive the boom. A fuse is usually provided to protect the motor.
The transmissions of the large concentrators manufactured by Doyle and Amcor use a hydrostatic oil film bearing device. The device is designed using the principle of hydrostatics, consisting of hydraulic oil film bearings, hydraulic bearing housings, internal gear transmissions and 3 to 4 worm gear drives and auxiliary facilities. The rotating body is supported on a sealed oil pad thrust bearing seat, and is filled with an oil film between the two, and has a thickness of about 0.125 to 0.25 mm. The oil is supplied by an oil pump. The rotor is driven by a worm gear for stable horizontal rotation on the oil film. Frictional force between the film only with a conventional thickener lubricating metal contact frictional force of 1/200. Thus torque transmitted is large, a uniform load transmission, stable and reliable, the concentrator promote large-scale development. [next]
(2) Type and performance of 耙 type thickener
The type of 浓缩 concentrator can be divided into two types, namely, the central drive concentrator and the peripheral drive concentrator.
A center drive concentrator
The central drive concentrator consists of a tank body, a feeding device, a truss, a transmission and its support (central column, center truss or caisson hollow column) and lifting device. As shown in Fig. 1 and Fig. 2, the tank body is a circular pool (groove) constructed of steel plate or reinforced concrete, and the bottom of the tank is horizontally or slightly inclined. The upper part of the trough is equipped with a transmission, a lifting mechanism and a truss for supporting. The truss for mining is placed at the bottom of the tank and connected to the central column truss or the central vertical axis. When the transmission drives the truss to rotate, the material deposited in the tank is scraped by the raft to the discharge opening at the center of the tank. When the raft is scraping the sand, the sediment is pressurized to facilitate the extrusion of part of the water. [next]
When the central transmission concentrator is working, the slurry is half-immersed in the center of the tank body and is immersed in the ore cylinder below the clarified liquid surface, flowing radially to the periphery (there is also a tangential direction to the ore in foreign countries), and gradually settles. The clarified liquid is removed from the annular overflow trough above the tank. When the amount of feed is too large or the concentration of the precipitate is too large, the safety device sends a signal to lift the truss by manual manual or automatic lifting device to prevent burning of the motor or damage to the machine.
The small center drive concentrator is characterized in that the arm is mounted on the central shaft, the central shaft is driven by a worm gear reduction mechanism, and a safety signal device and an automatic or manual lifting device are provided. Most of these trusses are straight-legged arms, but they are also spiral-shaped and involute. As shown in Figure 3.
At present, the small center drive concentrator manufactured in China has the specifications of 1.8 meters in diameter, 3.6 meters, 6 meters, 9 meters and 12 meters.
China's central drive concentrator series has planned large-scale concentrators with three sizes of 53 meters, 75 meters and 100 meters. There are also four types of medium concentrators with diameters of 16 meters, 20 meters, 30 meters and 40 meters. The former is equipped with an automatic lifting device, and the latter is equipped with an automatic or manual lifting device.
One end of the truss of the large central drive concentrator is mounted on the reinforced concrete outer wall of the central column truss or caisson center column, and the other end is supported by a steel arm and is also suspended by a steel cable below the smaller cantilever beam.
B Peripheral drive concentrator The peripheral drive concentrator can be divided into two types according to the truss support mode, namely steel truss support and cantilever support. The former drive frame is integrated with the truss, and the latter truss is completely supported by the cantilever.
The structure of the peripheral concentrator supported by the steel truss of the truss is shown in Fig. 4. The tank body is a pool constructed of reinforced concrete. The wall of the tank is cylindrical, and the bottom of the tank is inclined toward the center (generally about 12°). There is a reinforced concrete column in the center of the tank. One end of the drive frame is supported on the center column by means of a dry bearing, and the other end is supported on the ring track. The truss can be used as a sidewalk or a mine pipe (slot). The transmission mechanism causes the roller to roll along the track and drive the truss. The central column is equipped with a motorized slip ring, and the power supply is supplied to the motor through a brush, a slip ring, and a cable laid on the truss.
A large peripheral drive concentrator with a diameter of more than 15 meters is provided with a fixed rack along the track on the ring pool of the concentrating tank. The gear reducer of the transmission has a pinion meshing with the rack to push the trolley forward. An overload breaker is usually provided to protect the motor. They are equipped with automatic controls for detecting, displaying and adjusting the working condition of the concentrator to ensure safe operation of the equipment.
The small peripheral drive concentrator is driven by the friction between the roller and the track, so no special safety device is required. When the resistance encountered by the scorpion exceeds a certain limit, the roller slips and the scorpion stops moving forward.
The friction between the steel roller and the rail is small, and the roller slip, the wear is severe, and the maintenance is difficult. In recent years, Shenyang Mining Machinery Factory and related units have jointly developed a polyether polyurethane synthetic rubber wheel to replace the steel roller drive, which solves the problem of steel wheel slip and extends the service life by more than 1.3 times.
C Foreign-made concentrators Dorr-Oliver Inc. and Emco are among the world leaders in the production of concentrating equipment . The center drive concentrator currently manufactured has a maximum diameter of 183 meters. The truss supports three types: the central vertical shaft type, the central pedestal type and the central caisson type. The common central vertical axis and central axle type with a diameter of less than 100 meters; the central caisson structure with a diameter of more than 100 meters, and automatic control device for automatic lubrication, pressure measurement, temperature measurement and load measurement.
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