New trends in the mining and smelting process of sand ore and primary ore

I. New trends in gold mining vessels

Since the first application of dry gold in New Zealand in 1870, gold mining has made tremendous contributions to the production of world gold deposits and other heavy sand mines in the past 100 years. Among them, the main types of bucket-type gold mining vessels are more widely used, and many countries are still under construction and use. Since the chain bucket type gold mining vessel adopts the sprocket and the chain transmission, the bucket has a certain distance between each other, and the power consumption is large. Vertical and horizontal rotation is also not flexible. It can not dig the bucket and the bottom layer of compacted stone slate, resulting in gold mining river bottom cracks and pores do not rise steeply out. Moreover, the action of the bucket entering and leaving the ore layer is costly, especially when the ore is collapsed and the ore is collapsed and falls into the pit where the ore has just been dug. The gold particles in the ore that collapsed, especially the large-grain gold, will not be harvested because of the high density first sinking into the bottom of the pit. The equipment and the hull are bulky, mostly at 600t or above, and consume a lot of power. It is also necessary to install high-voltage lines from nearby substations. According to the introduction of the American Gold Council director Yin Jizhen, the United States has eliminated the chain bucket gold mining ship and replaced it with a single-toothed and double-tooth mining gold mining vessel.

The excavation gold mining vessel is similar to the suction-type gold mining vessel with a reamer. Its operating procedures are only excavation, suction and transportation. The homework is continuous and does not work. Excavating the pressure of the tooth point over 1000kg, it can excavate the rock with the gravel layer and limestone . The excavation or suction can be used to extract the gold particles and mud sand in the riverbed depression and crack. Its excavation arm can be moved horizontally by 90°, and the vertical direction adjustment is also convenient, and the ship has its own generator set. A ship with a depth of 9 to 11 m has a deadweight of only 30 tons and can float on the water surface to easily transfer the work site. This type of vessel can also clean the river and recover the sand and gravel for construction while collecting gold.

Second, the implementation of the "breaking and grinding" mining system

As we all know, the crushing speed of the crusher is much faster than that of the grinding machine, and the energy consumption of the crushed mine is also 75% to 88% lower than that of the grinding. If the ore can be fully crushed before grinding into the grinding machine, it can greatly improve the grinding efficiency. But so far, many of our beneficiation plants still use after a period of open seats ore crushing into the ball mill. This kind of operation is simple, and the extensive crushing operation is managed, so that the ball mill is too thick for the ore, the grinding time is increased, the grinding machine and the spare parts loss and the electric energy consumption are increased, the grinding technology rate is lowered, and the cost is increased. Especially in the production of gold and silver , gold is extremely fine particles. Many ores are ground to -200 mesh or even -325 mesh. The gold particles are still not effectively separated from the carrier minerals. It is especially important to use "multi-grinding and less grinding". In order to achieve more and more grinding, in addition to the existing mines to rationally change the equipment configuration, each mining machinery factory should develop a new type of efficient, energy-saving, easy to support crushing equipment.

According to statistics, in the energy consumption of many concentrating plants in China, the crushing accounts for 8% to 10%, the grinding accounts for 45% to 55%; the grinding cost accounts for 40% to 60% of the total cost of the plant, of which electricity consumption and iron Ball and lining costs account for 90% of the grinding fee. The energy consumption and cost of grinding are so high, mainly because the ore is too thick in the grinding block, the classification efficiency of the classifier is low, the cycle load of the mill is large, the quality of the iron ball and the lining plate is poor, and the surrounding rock stone is not removed before the crushing. Caused by other factors.

In terms of ore into the grinding block, according to the relevant information, the total energy consumption of the grinding is the lowest when the optimum mass of the ore is 13mm. However, in the actual production of many selected plants, the ore into the grinding block is often 45 ~ 70mm, and some small selection plants in more than 80mm. Although the grinding efficiency is affected by many factors, in the above case, the ore should be first caught in the grinding block. For example, the Erdao Gold Mine strengthens the crushing management. After the ore into the grinding block is less than 35mm from the original 50mm, the daily production capacity of the ball mill is increased by 8.9%, and the cost is reduced by 1 yuan/t. The Baiyun Gold Mine changed the crushing operation, and the ore ingrinding block was changed from the original 50mm to less than 35~30mm, which not only ensured the graded overflow fineness, but the concentrate grade increased by 6.81g when the ore grade decreased by 0.9g∕t. ∕t, the recovery rate of gold increased by 2%.

Third, give full play to the role of re-election in primary ore dressing

The re-election method, an ancient method for recovering gold and other heavy minerals from sand mines, has not only been used in sand deposits in recent decades due to advances in equipment and operation technology, but also in large quantities for replacing mercury prior to slurry flotation. The fine gold and fine gold dissociated from the monomer are recovered before the plate or gold mud cyanide leaching. The former can eliminate mercury damage, the latter can shorten the cyanide time and increase the gold yield. Both can produce finished gold in advance and speed up the capital turnover of the plant.

In the early stages of mining, the South African gold mine mainly used re-election-alkali method to recover gold. After the introduction of cyanidation in South Africa in 1890, the re-election method was replaced in many mines. However, subsequent practice has proved that although the cyanidation process is highly efficient, there are many advantages to using the re-election method to recover as much gold as possible in the grinding cycle. That is, (1) for the grinding of gold-bearing iron ore, it mainly ensures the dissociation degree of the gold in the package to prevent the gangue minerals such as quartz from being over-grinded; (2) collecting the monomer from the mill discharge port in the grinding cycle Dissociation of gold, can avoid it re-entry into the mill, so that the accumulation of gold in the gap of the ball mill liner is greatly reduced; (3) cyanide slurry after pre-re-selection of gold (completely collected by coarse-grained monomer) The gold content can be reduced by 50%, which is beneficial to shorten the cyanide time, facilitate the cyanidation operation and increase the gold recovery rate; (4) Capture and recover part of the gold in advance, which can accelerate the output of finished gold and accelerate the turnover of funds; (5) many South African gold veins contained 0.002 ~ 0.02g / t ore fines osmium iridium, if not lost to the gravity separation occurs in the tailings. Especially when dealing with gold-rich ore, it is more advantageous to insert a re-election operation in the process. Therefore, the re-election method can be applied to any ore containing more than 10g∕t.

For the above reasons, nearly two-thirds of the South African gold mines today employ one or more re-election methods. Among these plants, the most widely used are modified Johnson cylinder concentrators, belt grate concentrators, flat bed concentrators, corduroy chutes, and jigs. This type of concentrator is used in South Africa's selection of coarse gold, and the recovery rate of gold is as high as 75% or more. In other countries, the application of the re-election method is also quite extensive. In the past 100 years, many re-election equipments have been introduced at home and abroad. Some of the new and improved equipments have achieved good levels in terms of the lower particle size recovery and recovery rate of gold, as well as the simplification of working conditions, and each has its own characteristics.

The Johnson cylinder concentrator is a 3.66m continuous rotating cylinder with an axial inclination of 10% and the cylinder is lined with corduroy. The improved cylindrical concentrator is axially inclined by 2.5° to 5°, and the cylinder is lined with a serrated rubber strip parallel to the axial direction (see Figure 1). The strip is 3mm deep, 3.5mm wide and 3mm apart. The simplified direction of rotation is opposite to the serrated tip of the rubber strip, and as the slurry flows along the axial direction of the cylinder, heavy minerals are deposited in the bars. When it is rotated to the apex, the water sprayed from the sprinkler pipe flushes the heavy minerals into the concentrate tank. This type of concentrator is used to treat the discharge from the hydrocyclone underflow or the secondary ball mill. It is simple to operate and low in power consumption, and a 1 kW motor is enough to rotate the cylinder. Table 1 shows the specifications and operating specifications of three cylinder concentrators in South Africa. The produced concentrate is enriched by a belt-type strip concentrator and then mixed with mercury.

Table 1 Specifications and operating specifications of the Johnson cylinder concentrator

Figure 1 Johnson cylinder concentrator

The belt type strip concentrator, also known as the mechanical chute, is connected by a corduroy rubber strip to an infinite strip, and a selective concentrator for the coarse concentrate. The glue has a bandwidth of 1.52m and the belt is inclined by 10° to 12° (Fig. 2). The belt moving speed is reduced from 0.1 to 0.36 m/min by the gear reducer. The bars are 3mm high and have a pitch of 5mm. The flow direction of the supplied slurry is opposite to the direction in which the belt moves. The concentrate is collected in the grid to the lower part of the bed, and is flushed by water spray to the concentrate tank. The tailings are discharged from the bed at the end of the belt. The specifications and operating specifications of the belt type slag concentrator used in South Africa for processing concentrates of cylindrical concentrators and flat bed concentrators are shown in Table 2.

Table 2 Specifications and operation index of belt type concentrator

Figure 2 belt type strip concentrator

The flat bed concentrator has a three-stage stepped shape, also known as a three-stage flat bed concentrator. Since the machine has no moving parts and is not actually repaired, it has been used by many South African plants to capture gold from secondary ball mills. Such concentrators are usually used in series of 2 to 3 units. The bed surface is made of steel or wooden, and the rubber strips are laid vertically on the stepped bed surface. Below the ladder there is a transverse narrow groove to collect the concentrate flowing down the grid. The pulp flowing faster above the grid passes downstream into the next stage. The produced concentrate is further enriched by a James shaker or a belt type concentrator, and the gold is recovered by amalgamation. The specifications of the flat bed concentrator for South Africa and the operating indicators for secondary grinding and ore discharge are listed in Table 3.

Table 3 Specifications and operation indicators of flat bed concentrator

The corduroy chute began to be used in South Africa in 1922 to replace the amalgam plate. Because of its good gold-harvesting effect, it saves labor and mercury, prevents workers from stealing mercury and eliminates drooling (the symptoms of mercury poisoning), and is still widely used in South Africa. The chute bed and the bracket are made of concrete. The groove surface is 2.74m long and 1.52m wide. The area is large. Usually, the corduroy cloth is replaced by 4~h, and no special person is required to take care of the operation. It is widely used in the classifier circuit to capture monomeric gold.

The Nelson Hydraulic Concentrator is a centrifugal cone concentrator that has been developed in the last three decades (Figure 3). The cone is frustoconical, with an inner diameter of 762mm (35"). It consists of two layers inside and outside. The number of rotations of the cone is 400r/min and the power is 5.6kW. The inner cone is 50mm × 50mm (2" × 2"). Open the 1.6mm (1/l6") hole, the static pressure water is fed from under the cone, and enter the inner cone through the hole to form a "water pad" to keep the concentrate in a loose state, so that the precipitation is not too tight. The ore size is less than 6mm, the treatment capacity is 20~23m ³ ∕h, and the water consumption is 1.8m ³ /min. The centrifugal strength of the machine is about 300 times that of gravity, which enables the light mineral floating well to overflow from the upper part of the cone. The recovery rate of monomer gold can reach 95% to 99%, including some -560 ~ +625 mesh fine gold particles. Each time you can work continuously for 8~10h, or when the concentrated concentrate is about 200kg in the cone, stop the plug and rinse it with water for about 5min to unload the concentrate. Due to its high efficiency and easy operation, this machine has been widely used to replace gold amalgamation plates to recover gold from the ball mill discharge.

Figure 3 Nelson Hydraulic Concentrator

The Wrightke Cone Concentrator was originally developed for the recovery of gold from sand mines in Australia and was also very successful when used in the re-election of vein gold mines. It is characterized by a wide range of particle sizes for processing raw materials, up to 0.038 mm (400 mesh), and high recovery.

The Dutch round jig has a zigzag motion curve and can recover fine gold. The gold recovery rate for sand gold deposits is up to 94% or more, and the ability to process raw materials is large, which has become the main re-election equipment on gold mining vessels.

In foreign countries, there are still quite a lot of old and new rebuilt equipments that are widely used today, and will not be introduced here.

The plastic felt is a plastic belt-drawing machine fabric. The products are available in a variety of colors and thicknesses. They were originally used to lay sports grounds or to decorate indoor and outdoor lawns, also known as artificial turf. Canada first put it on the Rotary chute instead of carpets to collect gold particles, the effect is very good. In 1984, Heilongjiang Province introduced green plastic felts with thicknesses of 6mm and 20mm for the production of gold in the Longjiang-1 type chute. The catch rate of gold was increased by about 20% compared with sacks and carpets. Liaoning Hejia Gold Mine is a small selection plant located in a densely populated area. It is not suitable to use mercury plates. Instead of using plastic felt chutes, it can capture 16.4% of gold from the pulp. And the felt is elastic, easy to use and durable.

Engine cooling Radiator

A radiator includes a core for cooling a fluid, and a tank connected to the core having a side surface with a depression extending between the front and rear surfaces adapted to receive a hose and a plurality of integral ribs formed on the tank external surfaces. The radiator further includes an elongated support member having a body portion removably connected to the core and extending along a side thereof, an end portion removably connected to the tank, and a flexible expansion portion permitting relative movement between the body and end portions to reduce stress during thermal expansion and contraction of the core.

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