Application of X-ray in the field of ore sorting

2020-12-17

Metal ore refers to ore containing metal components. According to the types of metals contained and different grade, metal ores can be divided into:

A Classify according by different content of metals:
  1. Ferrous metal ore: such as iron, manganese, chromium, etc.
  2. Non-ferrous metal ores: such as copper, lead, zinc, aluminum, tin, molybdenum, nickel, antimony, tungsten, etc.
  3. Precious metal ore: such as gold, silver, platinum, etc.
  4. Radioactive metal ores: such as uranium, radium, thorium, etc.
  5. Rare metal ores: such as lithium, beryllium, cesium, etc.
B according to the level of metal content,

It can be divided into: lean ores and rich ores. Take magnetite as an example: open hearth rich ore with iron content greater than 55%, blast furnace rich ore with iron content greater than 50%, and lean ore with iron content of 30-50%. Lean ore must be sorted before smelting.

Currently commonly used sorting methods
  1. Magnetic separation method (that is, the method of using magnets and electromagnets for separation according to the strength of the minerals) suitable for magnetic separation methods include iron ore, manganese ore, etc.
  2. Gravity selection method, also called heavy medium selection method, is a method of sorting according to the different specific gravity of minerals and their different settling speeds in the medium. The ores suitable for gravity separation include tin ore, lead-zinc ore, pyrite, titanium ore and other minerals with a density greater than 4 or more.
  3. Electric sorting method, that is sorting method according to the difference of mineral conductivity. The principle is that when the mineral passes through the high-voltage electric field of the electric separator, the conductivity of the mineral is different. The electrostatic force on the minerals in the scope is also different, so the minerals can be separated. The ore suitable for gravity separation includes Wolframite ore, calcite, colorless and transparent quartz, etc.
  4. The flotation method is based on the difference in physical and chemical properties of the mineral surface, treated with a flotation agent, so that the mineral is selectively attached to the bubbles, so as to achieve the purpose of separation. Flotation is the most important separation method for ore dressing currently. At present, more than 90% of non-ferrous metal minerals are processed by flotation process. In addition, it is also suitable for ferrous metals and precious metals. According to the type of metal, copper, lead, zinc, sulfur, molybdenum, etc. and ferrous coal, etc.

Although the flotation method is currently the most widely used method in the field of ore separation applications, and the separation accuracy is also very stable. However, in recent years, with the continuous attention and supervision of the country's environmental pollution work, it has brought great challenges to the flotation method, and the cost of separation has continued to increase. Because the flotation method needs to use a lot of water resources, and after sorting, the water resources must be treated in harmless method. In recent years, a new ore sorting method has been continuously applied and promoted. This method is the X-ray fluoroscopy sorting technique. he following is a detailed introduction of this technology from three aspects:

A principle of x-ray sorting

The ore passes through the feeding device and is irradiated by the x-ray source in the x-ray fluoroscopy system at a certain speed. The x-ray detector is used to obtain the characteristics of the ore (the internal physical density of the ore), and the effective atomic number and other information are obtained through the corresponding algorithm. Then the obtained data is transmitted to the jet solenoid valve, and the ore is selected by high-pressure jet accordingly.

B advantages of x-ray transmission sorting
  1. No water, no media, so there is no need for dehydration, de-intermediation, water treatment, and media recovery system.
  2. Low energy consumption, which is more than 50% lower than the energy consumption of the flotation method.
  3. Less land occupation, saving investment.
  4. Significantly increase the utilization rate of ore (waste pre-discarding) and added value to help enterprises reduce costs and increase benefits.
The development history and domestic application of three x-ray transmission sorting
  1. The first application of X-ray transmission technology for mineral separation in the world was the Russian Rados (RADOS) Co., Ltd., which realized industrial application in the 1990s.
  2. Currently, coal, tungsten, manganese, lead-zinc, brass, rare earth, diamond and other industries have been widely used worldwide. The most mature companies in this field are TOMRA and STEINERT in Germany.
  3. The first application in China was Tianjin Meiteng Technology Co., Ltd., which realized the industrial application in the coal industry in 2016.
  4. In 2020, Tangshan XiangSu Intelligent Technology Co., Ltd. achieved a new breakthrough in the field of ore sorting based on x-ray transmission technology + neural network + laser recognition.

As of June this year, X-ray transmission sorting equipment has achieved more than 100 government procurements in coal, tin, tungsten, manganese, lead and zinc ores. Acccording to the prediction from third party, X-ray transmission sorting application has a market capacity of about 10,000 units.

In recent years, with the adjustment of national industrial policies and the continuous strengthening of environmental protection policies, most Chinese domestic mining enterprises have struggled, and the "mining winter" has become more and more obvious. On the one hand, demand continues to increase, on the other hand, labor costs continue to increase. The grade of ore is not easily to increase, meanwhile the difficulty of mining is fast increasing. Especially for low-grade mining companies,their whole future's on the line. Therefore, sorting equipment based on x-ray transmission technology is more and more welcome by the market, and the market prospect is promising due to it’s the best option to reduce the cost and increase the grade of the mining ore..