(Placer) gold exists in nature mainly in the free capillary gold mainly those nugget (bulky gold bath called) is extremely rare, we generally can be taken to the sand gold, the basic chunks of gold Mainly, even if it is a test, the simple gold pot wash test, the test results are small. In the mining of gold deposits, most of the fine gold was ran away, and how many ran away, no one knows. Different mines have different ratios of difficult gold selections (values â€‹â€‹between 5% and 70%). They can be selected very rarely. Why? Mainly because of the characteristics of gold and the methods and equipment we use.
What are the characteristics of gold? The gold of nature has a density between 15 and 19 g/cm 3 . Compared to other minerals, the re-election advantage should be outstanding. However, the characteristics of gold dust and granule are very different from other minerals, other heavy minerals such as lead zinc ore, even fine particles, but it has relatively strong shape, colloquially, that looks thick, more spherical The ratio of surface area to volume is small (the spherical surface area to volume ratio is the smallest of all geometries), and has good re-selection of particle size characteristics, but the gold is different. The sand gold is more of a thin skin type and looks more like a fly wing. Or mica , some are gold-stone or hollow type. These characteristics offset most of the density advantage of gold, and the ratio of surface area to volume of gold particles is very large, which greatly increases the difficulty of re-election.
Placer device we use, is substantially normal shelf-slip canal and gold mat (with gold felt), belong reselection apparatus (using a material different specific gravity separation equipment mineral matter), gold to a large volume, heavy weight, the effect of Very good, it is powerless to the thin gold, but why?
Pu slip and gold felt, because the weight of the bulk gold is much larger than its buoyancy and impact in the water, and can discharge the waste sand, quickly sink to the bottom of the tank, complete the beneficiation, and the small size of the fine gold, thin skin gold It's hard to sink quickly, and most of it is washed away. Why? The fluid mechanics in physics gives us a clear answer: the force that a solid particle receives in a fluid depends not only on its volume, but also on its surface area, which is proportional to the velocity of the fluid. That is to say, the force of capillary gold in the water flow is not only related to its volume, but also related to its surface area and water flow velocity. This phenomenon seems to be contrary to our usual common sense. We always think that as long as the density is greater than water, it will sink. (It is true, but it is in the ideal still water.) It is difficult to understand. In fact, there are examples. For example, sandstorms, sand particles (dust) are driven by airflow, and dust from Inner Mongolia can be drifted to distant Japan. However, the cobblestones in Inner Mongolia definitely cannot go to Japan. For example, our Yellow River can bring the fine soil of the Loess Plateau into the East China Sea, but it is difficult to bring the big stones of the wheel to the sea. This is because the surface of the rock is 10 million times larger than the original after grinding the fine powder. Increase, the final buoyancy is almost the same as gravity or even exceeds gravity, so there will be more than 2,000 times more weight than the air floating in the air wonders - sandstorms, there will be turbid waves of the Yellow River. By the same token, the surface area of â€‹â€‹the dog's head gold with a larger surface area of â€‹â€‹the fine gold thin skin gold has increased by a factor of ten, and the force in the water flow has also increased many times. The proportion of gold is 19.6 times that of water. The proportion of stone is more than 2,000 times that of air. Stones that are more than 2,000 times heavier than air (dust is also rock) can float into the air. Obviously, let the capillary gold in the mud sink. It is more difficult than letting the dust in the air fall to the ground.
Is there no way? No, there are ways.
Method 1, reduce the speed of water flow, just like the wind is small, the dust is small, the flow rate of the river is reduced, the sediment will sink, the river will be clarified; our peristaltic chute can partially slow down. Pu slip and gold felt can not reduce the flow rate of water, the water flow is small, it will be in the trough, so it can only be installed on a steep slope, the water flow is rushing, the flow is straight down, and the creeping chute, due to the power, makes the sediment not easy to accumulate. The installation slope is small, the sliding surface is not a flat plane, there are lattice teeth, grid and lattice eyes, the ore flow is forced to decelerate, the flow rate is reduced, and the capillary gold and thin skin gold are more likely to sink;
Method 2, dredge the sinking channel, is to overcome and solve the knot phenomenon, the knot phenomenon is a major problem of gold deposits, is the enemy of fine gold, especially thin skin gold, it is obvious that the thin skin gold like fly wings is almost impossible to drill Into the sand layer that is tied up. The creeping chute can completely solve the knot phenomenon. Pu slip and gold felt, just started working for a few minutes, the sediment at the bottom of the trough is on a dense and hard layer, and then the gold, especially the fine gold and thin skin gold, has almost no space to sink, can only fall on the knot On the surface of the layer, it is finally impossible to escape the fate of being washed away. (The terminology is called the knot phenomenon). The peristaltic chute completely overcomes the knot phenomenon due to its unique and novel structure, and the lattice teeth and lattice eyes on the plate make the water flow form numerous small eddy currents, which invisibly increases the mining time of the ore sand, and The stripping time of the sandstone mud has a forced leaching layering effect. In summary, two conditions have been created to create a good condition for the selection of fine gold and thin skin gold.
Method 3: Let the small proportion of the pro-gold (less than the proportion of water, such as oil) chemical substances wrap the fine gold, so that they rise together, and then choose the golden flotation method;
Method 4, chemical cyanidation method and mixed method.
In methods 3 and 4, private and small enterprises cannot be realized at all. The technical difficulty is large, the amount of funds is large, the environmental pollution is serious, and there is no economic feasibility. Policies and regulations are not allowed.
The peristaltic chute also includes the advantages of the processing capacity of the ordinary chute, and at the same time has the characteristics of the jig, which is the perfect combination of the chute and the jig, and a peristaltic chute, which is equivalent to the serial use of more than 20 jigs. The effect is of course very prominent. When the peristaltic chute is working, when it is topped up, the sand layer is loose, the water flow is increased, the mineral material moves and stratifies, and the light waste sand is â€œliftedâ€ to the top layer and washed away. When descending, the decrease of water flow speed is conducive to stratification and sinking. At the same time, a relatively negative pressure is formed at the lattice and the edge of the lattice, which has a "suction" effect on the mineral material, and the gold particles are forcibly sucked into the relative In the lower layer of the calm grid, (this is very similar to the jig), and the sand in the grid is very loose, there is no knot phenomenon, the gold particles and the golden skin will have space to continue to sink, each cycle Drop a little, wait for it to sink to a certain depth, it will be safe, no longer have to worry about being washed away, deeper and deeper, complete the beneficiation. But ordinary chutes simply can't do this. Therefore, the peristaltic chute has outstanding advantages in the selection of capillary gold and thin skin gold.
Creeping chute parameter
Shape: 1140 type, 1.3m*3.8m*0.8, effective area 1.14m*3.0m. 1800 type, 3.8m*2.2m*0.8m, effective area 1.8m*3.0m
Weight: 1140 type is about 0.75T.1800 type about 1.2T
Installation angle: The recommended angle of 40 is that the sand outlet is about 20cm lower than the sand inlet, which is obviously smaller than the angle of the slip. The actual installation should be adjusted according to the specific conditions of the site, so that it is not good for the slot.
Power: 1140 type 1.1kw4 motor. 1800 type 2.2kw4 motor.
Feed particle size: preferably less than 15 mm.
Installation method: It can be directly connected to the bottom of the sieve, or it can be connected to the lower end of the existing.
Scope: All gold sand, gold dredger; magnetic iron ore; tail veins of gold mud reselection.
Sand output: There are no strict restrictions, only reference data, type 1140, less than 12 cubic meters per hour. The 1800 is less than 18 cubic meters.
Water consumption: similar to the fixed chute, slightly smaller than the fixed chute, the small point has little effect.
Recovery rate: due to the difference in mineral quality, the actual use in Inner Mongolia (connected to the lower end of the 4 m ordinary chute) is about 5% to 15%. (Used in the upper reaches of the Jialing River, the recovery rate is as high as 20%. But there is only one case. Can't conclude because of this.)
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