Lead and zinc are key basic raw materials for modern social and economic development. Rapid economic growth is accompanied by an increase in demand for lead and zinc. However, the resources of high grade, good grindability, and easy to select lead and zinc ores are decreasing year by year. For complex and difficult to select lead and zinc ores, choosing new beneficiation equipment can make lead and zinc ore selection twice the result with half the effort.
Crushing and grinding operation is a high energy consumption and high steel consumption operation process in the entire lead-zinc ore beneficiation production line. In order to achieve the goals of energy conservation, consumption reduction, and production increase, attention should be paid to more crushing and less grinding.
Mobile crushing station
With the maturity of production technologies such as semi-automatic grinding machines and high-pressure roller mills, new crushing and grinding equipment has been studied and applied for different ore properties. The combination of crushing and grinding equipment such as crushing+rod mill+ball mill, crushing+semi-automatic mill+ball mill, crushing+semi-automatic mill+vertical mill, crushing+high-pressure roller mill+ball mill has been applied in lead-zinc mines, promoting the reduction of energy consumption and steel consumption in crushing and grinding operations, and also playing a positive role in improving dust and noise.
1.1. Common lead zinc ore crushing equipment
The commonly used crushing equipment mainly includes jaw crushers, rotary crushers, cone crushers, impact crushers, and high-pressure roller mills.
(1) Jaw crushers and rotary crushers are mainly used for rough crushing operations;
(2) Cone crushers and impact crushers are mostly used for medium and fine crushing operations;
(3) Two or three stage crushing with jaw crusher and cone crusher as the core is more common.
New crushing equipment such as high-pressure roller mills and mobile crushing stations are gradually promoting the transformation of traditional crushing methods for lead and zinc with their unique advantages.
The main development directions of crushing equipment are: large-scale, high-efficiency, and automated control, as well as the use of new structures, materials, and technologies to improve the performance of traditional crushing equipment, making advanced crushing equipment more prominent in terms of high efficiency, low energy consumption, and stable operation.
1.2. Common lead zinc ore grinding equipment
The commonly used grinding equipment mainly includes ball mills, rod mills, self grinding (semi self grinding) machines, etc.
(1) Ball mill: It has always occupied a dominant position and played an irreplaceable role in grinding, with a grid type ball mill used for one stage of grinding and an overflow type ball mill used for re grinding, which have been widely used in lead-zinc beneficiation plants;
(2) Rod mill: Soft, brittle, and easily mud prone ores can be aggravated by using a ball mill, while using a rod mill with a more uniform grinding force can reduce over grinding mud;
(3) Self grinding (semi self grinding) machine: With a large feed particle size and high crushing ratio, it can eliminate intermediate and fine crushing in crushing operations. It has the advantages of short process flow, small footprint, and low energy consumption, and produces less dust for wet crushing.
Self grinding machine
A new combination of grinding equipment: The Xitieshan Lead Zinc Mine beneficiation plant has renovated the grinding and classification system, replacing the original three stage one closed circuit crushing process and one stage one closed circuit grinding process with one stage coarse crushing+semi-automatic grinding+ball milling process. The grinding and classification operation was originally composed of four ball mills and spiral classifiers, and after renovation, it was transformed into one MZB5.0 m x 2.5m semi-automatic mill, one MQY3.8 m x 5.2 m ball mill, and one FX660 hydrocyclone.
After the renovation, not only did it save equipment investment, but it also reduced the energy consumption of grinding operations, improved grinding efficiency, and made the grinding process more concise.
2.1. Flotation cell
The main development direction of lead-zinc ore flotation cells is large-scale and automated control, introducing new types of flotation cells with composite flotation force fields such as centrifugal force fields and magnetic fields, as well as specialized flotation cells for coarse and fine particle flotation. However, due to the limited number of large and medium-sized lead-zinc mines in China, the scale of beneficiation plants is mainly small and medium-sized, and the application of large-scale flotation equipment is very limited.
Flotation cell
2.2. Flotation column
The flotation column belongs to the flotation equipment without mechanical stirrers, which has the advantages of simple structure, small footprint, and high ore concentration ratio. It is also suitable for the separation of fine-grained minerals. The flotation equipment widely used in lead-zinc beneficiation plants is the flotation cell, but with the development and progress of flotation column technology, flotation columns have gradually been applied.
The combination of new flotation equipment: the selection section uses flotation columns, while the coarse and sweeping sections use flotation cells, which has become an important mode of flotation equipment use. However, with the expansion of the particle size range of the flotation column or the overall fine grinding of the selected ore, some lead-zinc beneficiation plants have achieved the full flow use of flotation columns.
The above introduces the new beneficiation equipment for lead-zinc ore, including semi-automatic mills, high-pressure roller mills, mobile crushing stations, stirring mills, flotation columns, etc. Regardless of the equipment used, our ultimate goal is to improve the utilization rate of lead and zinc mineral resources, improve production efficiency, and reduce production costs. The application of new equipment in lead-zinc ore beneficiation plants is of great significance for promoting energy conservation and emission reduction.
