Liberation of valuable minerals in the ore is a crucial issue that any mineral processing method must first address. Therefore, flotation condition tests generally begin with grinding fineness tests. Based on the identification results of mineral dispersal particle size characteristics, the grinding fineness can be preliminarily estimated, but it must be finally determined through experiments.
The common practice for grinding fineness tests is to take three or more samples and grind them for different times (e.g., 10 min, 12 min, 15 min, 20 min, 30 min) while keeping other test conditions the same, then perform flotation and compare the results. Simultaneously, several ore samples are taken in parallel and ground at the previously specified grinding times, and the grinding products are sieved to determine the relationship between grinding time and grinding fineness. Sometimes, one or two conditions with better results can be selected, and one or two ore samples are ground and sieved for the corresponding time.
Flotation tests are generally conducted in two batches, with froth skimming performed. First, roughing is performed to scrape off the roughing concentrate. During this process, the reagent dosage and flotation time must be the same in all tests. Then, scavenging is performed to scrape off the scavenged froth product, i.e., middlings. In this process, the collector dosage and flotation time can vary to ensure all the desired minerals float to the surface, yielding the lowest possible tailings. If the endpoint of flotation is difficult to determine visually, the flotation time and reagent dosage for middlings should also remain the same in all tests.
The specific method for determining the relationship between grinding time and grinding fineness is as follows: After drying the ground product, take a sample (generally 100g) and wet-sieve it on a 200-mesh sieve. After drying the product on the sieve, place it on another 200-mesh sieve for inspection and sieving. Combine and measure the material smaller than 200 mesh obtained before and after sieving. Based on this, the content of -200 mesh grade minerals in the ground product can be calculated. Then, a graph was plotted with grinding time (min) on the x-axis and grinding fineness (content of -200 mesh grade, %) on the y-axis.
The flotation products were dried, weighed, sampled, and sent for chemical analysis. The test results were then recorded in a record sheet and a graph was plotted. The format of the flotation test record sheet depends on the purpose of the test and the composition of the ore. The general requirement is that it be clear and concise, facilitating analysis.