At present, there are three main methods for the treatment of iron ore dressing tailings: first, re separation and recycling of iron ore tailings; The second is to screen out useful factors to make construction materials; The third is to fill the goaf with iron tailings. Which of the three methods do you consider? Let's take a closer look.
At present, China produces about 110 million tons of iron tailings every year, and the average grade of tailings is about 11%. If the iron tailings are re selected and the iron concentrate recovered is calculated by 60% grade and 2%~3% yield, 3~4 million tons of iron concentrate can be obtained every year, which is equivalent to the output of a large iron ore enterprise concentrator.
Generally, at the current technical level, after analyzing the mineral composition of iron tailings according to their different properties, magnetic separation method, gravity separation method, flotation method and combined process flow are used to recover and re select the minerals with recycling value in the tailings to turn waste into treasure, which is not only conducive to protecting the environment, but also has a positive impact on the long-term development of the enterprise.
• Generally, 2-3 times of high intensity magnetic separation shall be carried out to obtain iron concentrate or titanium iron concentrate for magnetic separation of iron tailings;
• For gravity separation method, spiral chute is usually used for pre tailing, and then shaking table or centrifuge+high intensity magnetic separator are used for separation;
• The flotation method is adjusted by reagents and machinery. Due to different ore properties, the flotation methods used are different. The commonly used flotation methods include anionic positive flotation, anionic reverse flotation and cationic reverse flotation;
• When the separation capacity of a single method is low or the cost is too high, the combined process flow can be considered for re concentration of iron tailings. Common combined process methods include gravity separation magnetic separation flotation combined process and magnetic separation flotation combined process. Before iron tailings treatment, it is better to conduct beneficiation test on them and select appropriate treatment method according to the test report.
Tailings dry discharge is a process method to concentrate and dewater tailings, prepare materials with a moisture content (mass percentage) of 10% ± 2, and then transport them to tailings pond and waste dump for stockpiling or recycling.
Tailings dry discharge system is mainly composed of slurry pump, hydrocyclone, high-efficiency transformation thickener, high-frequency high-efficiency dewatering screen, box filter press and slurry conveying device.
The iron ore tailings are transported to the hydrocyclone for concentration and classification by the slurry pump. The settling sand of the hydrocyclone enters the high-frequency high-efficiency dewatering screen for dehydration, and the overflow enters the high-efficiency transformation thickener for concentration. Coarse tailings treated by high-frequency high-efficiency dewatering screen are transported to the stock yard for stockpiling by belt conveyor. Among them, the tailings after the thickening treatment of the thickener after the high-efficiency transformation are transported to the box filter press by the slurry pump for filtering treatment, and the filter cake of the filter press is unloaded to the belt conveyor to transport the fine tailings to the stock yard for stockpiling.
The dry discharge of tailings can reduce the water content of tailings to about 15%, relieve the pressure of tailings pond, reduce potential safety hazards, and greatly reduce the investment and energy consumption of technical system, with significant economic benefits, laying a foundation for realizing the mining vision of tailless mines and green mines.
In recent years, with the rapid development of filling mining method and filling technology, the iron tailings treatment method of tailings filling stope has been widely used for ecological restoration. Because some mine terrain is not suitable for building tailings pond, it provides an effective and economic method to fill the goaf with iron tailings.
There are two common methods for filling the goaf with iron ore dressing tailings:
(1) Full tailing cemented filling technology: this method mixes dehydrated iron tailings with cement, fly ash, etc. to form filling aggregate, and then sends the filling slurry to the mining and filling area for filling by pipeline self flow;
(2) High water consolidated full tailings filling technology: in this method, material A mainly consisting of aluminate and sulphoaluminate and material B mainly consisting of anhydrite, quicklime and coagulant are respectively slurried and transported, mixed before filling, and then the filling slurry is sent to the mining and filling area by pipeline gravity flow.
Another advantage of filling the goaf with iron tailings is to help the mine repair. Trace elements such as Zn, Mn, Cu, Mo and V contained in iron tailings are essential elements for maintaining plant growth and development. It can be seen that planting vegetation on iron tailings is not only conducive to stabilizing and reducing water and soil loss, but also can promote the growth of vegetation and effectively restore the ecological environment of the region.
The tailings of iron ore beneficiation contain harmful substances such as beneficiation reagents. If the tailings are discharged arbitrarily, the environmental pollution will be irreversible. The comprehensive recovery and utilization of iron tailings is a project beneficial to human society and the environment. The above provides three treatment methods of iron ore dressing tailings for reference.
