How to choose economical and reasonable mining methods for different mines?

 Mining method is the core of mining. It can be said that the choice of mining method determines the operation of the entire mining system. The selection of a correct and reasonable method of mining for a mine plays a decisive role in the future production and operation of the mine. Inferiority determines the mining efficiency, production scale, ore recovery rate, and ore quality of the mine. The method of mining is restricted by many factors, such as the geographical location of the ore body, the stability of the ore rock, the type of ore, the taste of the ore, and the depth of burial.

Although the burial elements of mineral deposits vary widely, in general, some rules can be summarized for the selection of mining methods, which are mainly divided into the following four situations:

1. If the buried depth of the ore body is shallow, and the extension depth is also shallow, all deposits are mined in open pit.

2. If the buried depth of the ore body is very deep, underground mining is adopted for all deposits.

3. If the burial depth of the upper part of the ore body is shallow, and the extension depth is very deep, the upper part of the ore bed adopts open-pit mining and the lower part adopts underground mining. In this case, in the middle of production, a transition period from open-pit mining to underground mining is needed.

4. The upper part of the ore body has a deeper buried depth, and the extension depth is shallower, all of which may be open-pit mining or all underground mining.

Failure analysis of ZGMn13 liner of ball mill

 Through the macro inspection and the onlooker inspection, it can be found that the liner of the ball mill will occasionally show loose casting, oxides, and a large number of massive unmelted carbides and needle-like carbides.

    The ideal microstructure of high manganese molten steel after treatment is a single austenite, but due to the metallographic examination of the liner, there are a large number of unmelted massive carbides and precipitated needle-like carbides in the microstructure. This is because the heating temperature is too low during the water toughening treatment, or the holding time is too short, so that the carbides are not fully integrated into the austenite. In the subsequent quenching and cooling process, a large amount of precipitation may be due to insufficient cooling speed. Needle carbide. From the field investigation, the heating temperature of the heat treatment furnace will be lower than the temperature required by the process due to long-term neglect and maintenance; when the water toughening treatment is cooled, because the water tank is too small, the treated tonnage is too heavy. The water temperature after cooling cannot be kept below 60 degrees Celsius, which reduces the cooling rate; if the workpiece stays in the water for too long from the furnace to the water, these will make the microstructure after the water toughening treatment appear abnormal.

    The chipping of the liner of the ball mill is mainly due to the improper longevity of the heat treatment process, the defective structure and casting shrinkage, as well as the existence of coarse non-metallic debris, which reduces the strength and toughness of the liner. Under the action of this, it will lead to the early failure of the liner.

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Movement form of hydrocyclone fluid

The hydrocyclone is a separation device that uses the principle of centrifugal sedimentation to separate or concentrate the slurry. Because of its simple structure, large workload, high separation efficiency, low cost, and low maintenance cost, it has been widely used in mineral processing, petroleum and chemical industries. The structure and size of the hydrocyclone are very important for separation. The diameter and underflow of the hydrocyclone are very important parameters that affect the working capacity and separation efficiency. For a larger cyclone diameter, the separation efficiency is low, but the working capacity is high. Therefore, if the separation efficiency of the large-diameter separator is satisfied, it is preferred. For solid-liquid hydrocyclones, increasing the underflow will increase the flow rate of the underflow. However, if the amount of underflow is too large, a large amount of water will flow out from the outlet of the underflow pipe, thus impairing the function of the underflow pipe. On the contrary, if the underflow diameter is too small, it may block solid particles, especially when the feed slurry is disturbed by a large concentration. Therefore, designing a proper hydrocyclone diameter and underflow pipe size is the key to improving the separation efficiency of the hydrocyclone.

                            

The structure of the hydrocyclone looks very simple, but the requirements for its structure, productivity, and grading effect are very high, and high matching degree can improve efficiency and productivity. Structural factors directly affect the flow form and movement mode of the fluid inside the cyclone. The fluid movement in the hydrocyclone mainly has the following forms: internal and external swirling flow, under-cover flow, balanced flow, and zero-speed envelope surface. The direction of rotation of the inner and outer swirling flow is the same, both clockwise or counterclockwise, but the direction of rotation of the swirling flow is opposite, the outer swirling flow is from top to bottom, and the inner swirling flow is from bottom to top. The underflow of the cover is also called short-circuit flow. It is due to the centrifugal force and the frictional force of the inner wall of the cylinder, a small part is suddenly released under the influence of the nozzle and pressure, first hits the top cover and then moves downward, and finally overflows with the overflow. The flow port is discharged, because this part of the slurry is directly mixed into the overflow without separation, so it directly affects the separation effect. The balance flow is two streams of two-phase fluid rotating inside and outside. Due to the different sizes of overflow ports and different insertion depths, there is no time for the slurry to be discharged from the upper and lower discharge ports, and the part of the slurry fluid that is not discharged is overflowing Between the tube and the cylinder, there is a balanced vortex movement up and down to form a balanced vortex. But this part of the exercise generally does not affect efficiency. The zero-speed envelope surface is due to the different movement directions of the inner and outer swirling flows. The inner swirling flow is formed by the movement of the outer swirling flow. Relatively speaking, there is a separation surface, that is, there is a fluid separation track with an axial velocity approaching zero. surface.

∅The realization of 4.5mx6m overflow ball mill electric control system

Overflow https://clactononseaessex.uk are widely used in cement, mining and thermal power generation industries due to their simple operation and low maintenance costs. With the development of society, the ball mill has made great progress in overall performance. The ball mill electrical control system is the central system of the entire ball mill, used to control various operating techniques.

  The control system mainly includes:

(1) Control of temperature measurement of bearings and stator windings;

Each mill has three temperature measurement points for the main bearing at the feed end, the main bearing at the discharge end and the stator winding of the main motor, and the pinion bearing and the main motor have two temperature measurement points. At the same time, the status value of each point can be displayed in real time on the man-machine interface connected to the PLC, and the alarm value and shutdown value of each measurement point can be given.

(2) Control of the main bearing high and low pressure lubrication station

   The main bearing high and low pressure lubrication station includes high pressure oil supply and low pressure lubrication. The high pressure oil supply system of each station supplies two high pressure pump motors. When any high pressure pump fails to work or the oil pressure is low, the backup pump will automatically replace the original work. The pump works and continues to supply oil to the main bearing.

(3) Pressure control

The high-pressure system of the lubrication station is equipped with four pressure sensors to detect the high-pressure oil supply system in real time. When the oil pressure is lower than the lower limit setting value, the sensor will send out an audible and visual alarm signal and limit the start of the host; when it is higher than the upper limit value When the sensor will send out an audible and visual alarm signal.

(4) Oil flow control

Install a flow switch in the low pressure oil supply system near the two main bearing oil supply points to continuously monitor the oil supply flow at each point.

(5) Oil temperature control

There is no electric heater or cooler on the lubrication station, and the oil temperature is given an obvious display signal by the bimetal thermometer through the electric control system to automatically turn on the electric heater or the cooling water valve.

(6) Control of slow drive motor

The slow-speed drive motor and the main motor are interlocked with each other, and they cannot work at the same time; when the slow-speed drive motor is working, the high-voltage oil supply system should be in a normal working state.

Choose a ball mill or a rod mill?

Grinding operation is very important in the entire beneficiation process, the cost is also quite large, the investment is huge and the energy consumption is high, therefore, choosing a suitable mill is very important for the entire beneficiation plant.

At present, ball mills and rod mills are widely used in concentrators. However, the difference in appearance between ball mills and rod mills is not very large, and it is not easy to distinguish. However, a careful comparison shows that the difference between the two is still very large. First of all, from the point of view of the name, the grinding medium of the ball mill is a steel ball, generally less than 100 mm in diameter, and the grinding medium of the rod mill is a steel rod, generally greater than 500 mm in length. The discharge methods of the two are also very different. The ball mill has two types of discharge methods: grid type and overflow type. Both have advantages and disadvantages. The rod mill has no grid plate, and mainly has overflow type and opening. Two types. Secondly, the filling rate of the grinding media is also different, that is, the percentage of the equipment volume occupied by the grinding media is different. If the filling rate is too high or too low, the final effect will be affected. Usually, the ball mill is 40%-50%, and the rod mill is 35%. -45% is the most ideal. The performance of the two equipment is also quite different. Due to the different media, the rod mill grinding media is in linear contact with the ore, which has a certain selective grinding effect, the product size is more uniform, and there is less over-grinding. The ball mill media and the ore are in point contact, which has impact and grinding power, and the product size is finer, but the over-grinding phenomenon is more serious. Finally, the scope of application of the two is also different. When heavy separation or magnetic separation of tungsten tin ore and other rare metal ores, rod mills are often used to prevent excessive crushing; in the second-stage grinding process, rod mills are generally used As the first-stage grinding equipment, it has larger production capacity and higher efficiency. When processing soft or not too hard ores, rod mills can be used to replace short-head cone crushers for fine crushing, which is not only simple to configure, but also low in cost, and simplifies dust removal in the workshop.

Because of the fine grinding materials, the ball mill is prone to over-crushing. It is not suitable for the gravity separation production line in metal beneficiation, but is widely used in other beneficiation processes.

Due to the difference between ball mills and rod mills, users can choose according to their materials, grinding particle size, production methods, etc. In contrast, the products of ball mills are finer and the products of rod mills are rougher but more uniform.

What are the equipment needed for gold mining

 Gravity separation is an older method of beneficiation, which uses different settling speeds of materials in the medium for separation. For placer gold mines, due to mechanical and weathering effects, the gold-bearing parent rock is gradually broken into granular objects such as cuttings. Under the action of external force, minerals with larger specific gravity are deposited on river beds, mountain slopes and other places to form Enriched. For the sorting of placer gold ore, re-election is a more direct and economical method, and the beneficiation process of re-election includes cracking, screening, dehydration, separation and other stages. Reselection methods include jig selection, shaker selection, chute selection, centrifugal selection and other processes. These gravity separation methods are mostly used in placer gold ore with monomer dissociation, and are rarely used alone. They are generally used in combination with other processes to recover gold ore more effectively. The following briefly introduces the equipment used for reselection.

1. Jig

The jig uses water as the beneficiation medium and uses the difference in the specific gravity of the selected minerals and gangues for separation. The Xinhai mineral processing jig is improved on the basis of the traditional jig, so that the jigging pulse curve is in a sawtooth waveform, and the rising water flow is faster than the falling water flow, so that the heavy mineral particles in the mineral can be fully settled and the recovery rate is improved.

2. Spiral chute

The main equipment of the chute for gold selection is the spiral chute, which is sorted with the help of inclined water flow. Its working characteristic is that the end of the tank is concentrated, medium ore, and tailings, without flushing water during the sorting process. The position of the regulating valve block is used to change the cutting width of various products. The change of the cross-sectional curvature of the spiral chute is particularly suitable for the selection of fine-grained materials. The beneficiation chute can be lined with FRP, wear-resistant rubber, and polyurethane rubber for users to choose independently.

3. Shaker

The shaker is a device for sorting in a horizontal medium flow, which uses the asymmetric reciprocating motion of the bed surface to realize the sorting of light and heavy minerals. The ore particles are fed into the ore tank, and at the same time, horizontal flushing water is supplied from the water supply tank. Under the action of gravity, impulse, friction, etc., the ore particles are layered according to specific gravity and particle size, and make asymmetrical reciprocating movement along the bed surface. Discharge from different areas to get different products.

Treatment experience of bolt fracture of large gear ring of 3.2mx13m mill

Frequent bolt breakage is a phenomenon that often occurs during the working process of the mill. The reason for bolt breakage is that the manufacturing size of the large ring gear does not match the original design, and the rigidity of the ring gear is insufficient, which will cause the running track to appear elliptical and the large ring gear The excuse bolt is subjected to a lot of shearing force and breaks.
In order to strengthen the fastening capacity of the bolts, we will adopt larger grades and higher strength bolts to ensure its strength. When checking the broken bolts, it was found that the nuts of the broken bolts had a small or trace amount of polishing. It can be judged that the bolts were loosened first and then broken. If you can ensure that the bolts are not loose, or reduce the impact of the bolts, the problem may be solved.
To prevent loosening, you can try positive and negative buckle bolts and nylon composite nuts. You can do the following:
(1) Change the bolt structure. The original M60x300 single-head bolts and M60x380 stud bolts can all be selected from M60x380 positive and negative buckle double-headed studs with positive and negative buckle nylon composite nuts on the inside, and 40Cr for the outer back nut is better.
(2) Strengthen maintenance. After running for a week or a month, fix the bolts 2 to 3 times to prevent them from loosening. The tightening force should ensure that the inner nylon composite nut does not crack.

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