In ancient China, the natural hydrophobicity of mineral surfaces was used to purify mineral drugs such as cinnabar and talc, so that mineral fine powder floated on the water surface and useless waste stone particles sank into the water. When panning placer gold, oil-soaked feathers are used to catch oleophilic and hydrophobic gold and silver particles, which was called goose feather scraping gold at that time. Song and Ming Ying Xing's Heavenly Creations records that when gold and silver powder is recovered from discarded utensils and dust, the gold and silver workshop "drops a few drops of oil and sinks with it". This is the initial application of gold flotation.
18th century, it has been known that solid particles can rise to the water surface through attached bubbles. With the increasing demand for metals, people are eager to find a way to recover metals from ores. At the end of 19, with the deepening of people's understanding of mineral surface properties, film flotation and all-oil flotation appeared. At the beginning of the 20th century, foam flotation was used to separate nonferrous metals from gold ores.
The foam flotation method used today originated in Australia about a century ago. 19 1 1 established the first flotation plant in Montana basin, USA-Gufeng concentrator. Up to1980,239 flotation plants consumed 772,000 tons of flotation reagents and 6.56 billion kwh of energy, and treated 440 million tons of ore. 1980 consumed 383,000 tons of flotation reagents, and 205 million tons of copper ore produced 420,000 tons of concentrate. The ore with the second largest capacity is phosphate ore-/kloc-0.09 million tons, which consumes 227,000 tons of chemicals and produces 26.6 million tons of phosphate concentrate. Flotation is the main method for iron ore production, with 38.9 million tons of ore producing 210.5 million tons of iron concentrate and consuming 6 1 10,000 tons of flotation reagents. Because about 2 billion tons of ores are treated by flotation all over the world, foam flotation is obviously one of the most important applications of surface chemistry in technology, especially for controlling liquid-solid interface. Successful flotation separation depends on the interaction between solid particles and bubbles in liquid medium. The key to selectively separate useful minerals from a large number of complex minerals (our mineral resources) is to improve the interaction between water molecules and mineral surfaces by adding appropriate flotation reagents and pH regulators. Foam flotation is not from theoretical research, but the result of accumulated experience in this century. Most, if not all, theoretical studies are used to explain the good performance of existing processes. Most basic research on mineral processing and metallurgy has the nature of post-inspection research, or it is a "tracking science" as described brilliantly by Fleming and Kay Chenel.
The appearance and development of flotation method also promoted the development of gold mining industry, especially created conditions for the utilization of vein gold ore and the comprehensive recovery of gold in non-ferrous metal ore. At present, flotation has become an important process to treat gold ore to produce gold. Many vein gold ore dressing plants in China mainly adopt flotation process or single flotation process. The recovery rate of gold in flotation plant is over 90%, and low-grade polymetallic mainly containing gold can be comprehensively recovered.
Fine gold less than 10um is difficult to be recovered by gravity separation. Based on the difference of physical and chemical properties of mineral surfaces, fine or even fine-grained minerals can be collected by flotation. Fine-grained gold can be recovered by ultrafine particle flotation or support flotation and ion flotation.