Flotation test pre-operation

Preparation, test equipment and operation technology of flotation samples

Laboratory flotation tests, usually referred to as "small unit flotation tests", are also referred to as "batch flotation tests."

Natural ore is generally used for testing, but when exploring a new prescription, or when studying the basic theory of flotation, a pure mineral flotation test is often performed.

First, sample preparation

1. Fragmentation and sampling

Considering the representativeness of the sample and the efficiency of the small mill, the particle size of the flotation test is generally less than 1-3 mm; therefore, the sample taken from the mine must be broken, usually crushed to about 6.5 mm by a jaw crusher. Then, the roller mill and the vibrating screen were used to cut the particle size required for the flotation test. The crushing process tries to avoid the loss of dust, especially when the grade of dust is high.

Broken sample aliquots into individual bags to be stored, per sample weight of 0.5 to 1 kg, an individual low grade rare metal ore with up to 3 kg. For the reduction of fine materials, a two-pointer (multi-slot divider) can be used;

2. Storage

When in the ore containing sulfide ores, particularly those containing a large amount pyrrhotite, oxidation may have a significant effect on the ore flotation test results. Therefore, the test of the sulfide ore is preferably carried out immediately after the sample is prepared. However, delays are often inevitable and measures must be taken to reduce their impact. The simple and easy way is to seal the storage under a coarser particle size (such as 6~25mm), then break the ore and prepare the sample several times, and process it in the same way every time. At the same time, it must be compared and tested. The possible difference in nuclear storage time and particle size from the test results. Stored specimens should be placed in a dry, cool, well ventilated area. Another solution is to prepare enough samples for the entire research project at a time and store them in an inert gas.

During the preparation of the sample, it is necessary to prevent the sample from being contaminated. The mixing of a small amount of oil will affect the normal operation of the flotation. The contamination of the oil and other materials should not be avoided. The pollution may come from the taking and transportation of the sample; or from the sample. Machine oil leaked from processing and shrinking equipment; or materials and chemicals left in the equipment from the previous test.

3. Grinding

The laboratory commonly uses a cylindrical grinding machine with an inner wall size of 160 X 180 mm, 200 x 200 mm, and an XMQ-67 240 X 90 cone ball mill , which are used for grinding samples with a particle size of less than 1 to 3 mm. . There are also smaller cylindrical barrel mills and roller mills, such as 100 X 150 mm, which are used for regrinding of medium and concentrate products.

Grinding media are customarily used with balls ranging from 12.5 mm to 32 mm in diameter. For the 160 x 180 磨 mill, the ball diameter of 25, 20, 15 mm is selected. For the XMQ-67 240 X 90 cone ball mill, it can be equipped with a larger (28~32 亳) ball. A 12.5 mm ball is generally only used for regrind operations. When using a rod as a medium, the diameter of the rod is 10 to 25. For example, the XMB-68 type 160 X 200 mm rod mill is often equipped with 17.5 and 20 mm rods.

In principle, the filling volume is preferably 40 to 50% of the volume of the grinding machine. When the diameter of the grinding machine is too large, the filling rate can be lower, because too much loading is often inconvenient to operate. The ball mill speed is too high, even when the critical speed is exceeded, the filling rate should be lower.

There is no specific rule for the ratio of balls of various sizes. According to our experience, the diameter 160 ball mill uses three balls of 25, 20, 10 mm to ensure a uniform particle size and a small size, but it is not easy to obtain a very fine product. When the ball is used for a long time, the concentration of the antimony ore should not be too high, otherwise the product will be oversized due to insufficient impact force. When fine grinding, the ball should be added. When a ball larger than 25 mm is required, the amount of the ball is generally not more than 40% of the total weight.

If the test is to avoid iron pollution, a ceramic ball mill can be used and ceramic balls can be used as the medium, but the ceramic grinding machine thus requires a longer grinding time. Grinding efficiency is low,

The grinding concentration varies with the nature of the ore, the size of the product, the type and size of the mill, and the operating habits of each research unit. The commonly used concentrations are 50, 75%, 67, and the liquid-solid ratio is 1:1, 1: 2, 1: 3, so the calculation of water addition is relatively simple. If other concentration values ​​are used, the amount of grinding water can be calculated as follows.

In general, when the ore is coarser and harder, a higher grinding concentration should be used. If the ore contains more mud, or the ore has a small specific gravity, or the product has a very fine particle size, a lower concentration can be used. In actual operation, if the product is found to be uneven in particle size, consider increasing the concentration (note that the large ball should not be too small when the concentration is high.) Conversely, the product is too sticky, and it is difficult to wash it on the wall and the ball. .

When the specific gravity of the sample is large or very small, the grinding water can be calculated as the solid volume accounts for 40~50% of the total volume of the slurry.

For long-term use of grinding machines and media, rust must be pre-ground with quartz sand or the sample under study before testing. Usually, you can dry it for a while before using it, and then start the test after washing the rust. The test must be completed with lime water or water.

In the test, the ball of the washed rust is first put into a clean grinding machine, then the water is added and the ore is added. It is also possible to leave a part of the water added at the end, but it is not possible to add water after adding the ore first, which will cause the ore to adhere to the end without being easily ground. When grinding, pay attention to whether the grinding machine's rotation speed is normal and accurately control the grinding time. After grinding, the slurry is poured into the ore container, the grinding machine is tilted, and the inside of the grinding machine is washed with a fine water stream by washing the bottle or the rubber tube connected to the faucet, and the ore is washed into the ore container. If the grinding machine such as 160 X 180 mm does not have a ball screen, it is necessary to put a ball screen on the receiving wall and separate the ball. After the inner wall of the grinding machine is washed, lift the ball. Sieve, while shaking, rinse the ball with a fine stream of water, until it is washed, and finally return the ball to the mill for next use.