The rate at which the leachate penetrates into the interior of the ore depends on the porosity and wettability of the ore. In homogeneous ore (such as granite porphyry), the leaching solution penetrates into all directions of the rock; in the rock developed by the fracture, the leaching solution first enters the main fracture and then enters the secondary fracture and capillary pores. There are many methods for determining the ore porosity, such as determining the effective porosity of the ore by weighing the dry sample amount and the amount of water saturated sample. A method of measuring the diffusion (or permeation) of the leaching solution in the ore may be carried out by a tracer atom method, a solution dyeing method, a conductivity method, or the like. The tracer atom method is more complicated and requires more instruments. The latter two methods are intuitive and simple, although their measurement accuracy is not high, but check each other several times, it can still meet the actual work needs.
First, solution dyeing
Grind a small groove in the center of the upper surface of the homogeneous ore to be tested, and then gradually drip the dyeing solution into the small tank so that the solution in the tank neither overflows nor dry, preferably the liquid level of the dyeing solution in the trap is always Keep it constant. The dyed band formed by the diffusion of the dye solution to the surroundings was observed day by day. If necessary, the ore can be sliced ​​and chemically analyzed to check the depth of diffusion (penetration) of the solution. Pavlov et al. used a dyed sulfuric acid solution to test granite porphyry ore with a Platts hardness of 10 to 15. The measured data are as follows:
table
Distance to spread downward (mm) | 20 | 30 | 40 | 60 | 100 |
Speed ​​of diffusion (mm/h) | 0.14 | 0.08 | 0.05 | 0.005 | 0.005 |
Second, the conductivity method
First, a small groove is made on the upper surface of the ore to be tested, and then at a certain distance on the side of the ore, several small holes that do not communicate with each other but penetrate into the inside of the ore are drilled, and electrodes are buried in these small holes. Then, as in the solution dyeing method, the solution is continuously added in the small tank, and the liquid level is always kept constant, and the conductivity is periodically measured. Figure 1 is a measurement schematic, and Figure 2 is a diffusion of sulfuric acid solution in five different mineral rocks.
Figure 1 shows the method for determining the permeability of the solution in the ore
a) Conductivity method 1-granite porphyry rock block; 2-solution small groove; 3-electrode
b) Solution dyeing method Above: Granite porphyry sample, after 1 month
Below: Granite porphyry samples, after 3 months
Fig. 2 Variation of the moving speed (v) of sulfuric acid solution along the surface of the ore to the probe (L)
l- felsitic porphyry; 2- granite; 3- clay slate;
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It can be seen from Fig. 2 that although the diffusion rate of the sulfuric acid solution in different ores is different, the common trend is that the solution has the highest diffusion rate at about 10 mm from the surface of the ore, and the speed is lower as the distance increases. . For ore with porphyry porphyry-porphyry, porphyrite and granite with an effective porosity of 0.89% to 1.1%, the penetration velocity at a depth of 10 mm from the surface of the ore is 0.1 to 0.16 mm/h. The permeation speed at 50mm is 0.007~0.04mm/h; for the shale and rough-faced Yingan rock ore with effective porosity of 0.61%~0.72%, the penetration speed is only 0.003mm/h at depths up to 50mm. .Medium Chrome Cast Grinding Iron Ball
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