In a tungsten ore old beneficiation plant, the processing capacity of the milling system is 700 t/d, employing 5 units of (rod) ball mills to form a two-stage milling process. The drawbacks of this milling system include a complex process, high energy consumption due to multiple devices, small processing capacity per unit, and high maintenance costs. To alter the current state of the plant, a large-scale transformation of the ball mill equipment becomes imperative.
The first-stage milling plant of the tungsten ore beneficiation plant has dimensions of 36m × 12m, with five (rod) ball mills providing a processing capacity of 700 t/d. The five units are: 1 GZM2136 ball mill, 1 MBS1530 rod mill, 1 MQG1530 ball mill, 1 MQY1530 ball mill, and 1 QYZ2130 ball mill.
The tungsten ore, with a rich ore content above 0.30%, is considered as exploitable resources. The total reserves of rich ore in the entire area are 5,062,454 tons, with a WO3 metal content of 27,415 tons and an average tungsten geological grade of 0.54%. Although the flotation process is mature, the milling system incurs high costs, impacting economic benefits. Hence, a transformation of the milling system is proposed.
After repeated comparisons and experiments, the chosen transformation plan involves dismantling all milling and grading equipment in the old beneficiation plant's first-stage milling platform. It proposes the installation of a large MQG3660 grid-type ball mill for milling and the use of a linear vibrating screen combined with a hydrocyclone for joint control grading.
The discharge of the ball mill utilizes a linear vibrating screen for screening. Material on the screen returns to the MQG3660 ball mill to form a closed-circuit milling system, while material under the screen enters the sand pump pool and is injected into the hydrocyclone group for classification. The overflow of the hydrocyclone enters the flotation process, and the sediment from the hydrocyclone enters the MQG3660 mill for further milling.
In this plan, the linear vibrating screen has a screen hole size of 3 mm, and the overflow particle size of the hydrocyclone is controlled at -74μm 71.50%. After the large-scale transformation of the mill, the processing capacity can reach 1300 t/d. With a calculation based on 300 working days per year, the cumulative annual processing ore volume is 390,000 tons, and the service life of the mine is 15.62 years.
Due to the brittle and easily pulverized nature of tungsten minerals, the transformation retains two-stage milling. It combines the first-stage milling with a linear vibrating screen and a hydraulic cyclone for dual control grading, using a grid-type ball mill. This effectively avoids over-grinding and under-grinding of tungsten minerals, resulting in a significantly improved milling effect.
After the transformation, only three ball mills are retained in the milling system, with the transformed MQG3660 ball mill replacing the three (rod) ball mills in the first stage of milling. This one-to-three replacement reduces energy consumption and saves costs.
The original milling system of the tungsten ore beneficiation plant could process 700 tons of raw ore per day. After the large-scale transformation, the daily processing capacity reaches 1300 tons, achieving both reduced consumption and increased production.
The transformation plan for the tungsten ore milling system, without expanding the original milling workshop, replaces three original first-stage milling devices with a single large MQG3660 ball mill. This plan offers advantages such as cost savings, small land area requirements, reduced personnel requirements, and a simplified process. If you also have an old beneficiation plant that needs equipment transformation on a large scale, you might consider referring to this case study or entrust the task to XinHai.
