Processing Units of Iron Ore Concentrate Plants
1. Introduction to Concentrate Plants and Infrastructure
The feedstock for Concentrate Plants Phases 1, 2, 3, and 4 is supplied from the output of five dry pre-processing lines. The incoming material undergoes two or three stages of crushing (jaw crusher and hydrocone) and is classified into different particle size ranges using screens. Through physical separation methods (magnetic separation), high-grade iron ore is separated from low-grade waste and prepared for feeding into Concentrate Plants Phases 1, 2, 3, and 4. The following sections provide a detailed overview of each plant and its processing methods.
1.2. Concentrate Plants Phases 1 and 3
In Phases 1 and 3, materials are discharged from under the stockpile via feeders onto conveyors that direct them to the chute of the primary ball mill. The first grinding stage occurs in the ball mill with a power consumption of 465 kW, reducing particle size from 7 mm to 0.5 mm. The mill output is classified by a primary hydrocyclone into two size fractions. The coarse fraction recirculates back to the primary mill, while the fine fraction is pumped to the secondary hydrocyclone.
The coarse fraction of the secondary hydrocyclone is transferred to the secondary ball mill, and the fine particles proceed to magnetic separation, which includes two parallel low-intensity magnetic separators. The concentrate from the separators is sent to product dewatering (disc filter), while the tailings are directed to the tailings thickener and then to the filtration circuit. Further infrastructure processes are explained in subsequent sections.
1.3. Concentrate Plant Phase 2
In Phase 2, materials are similarly fed from under the stockpile via feeders onto conveyors leading to the primary ball mill chute. Grinding occurs with 465 kW power, reducing particle size from 7 mm to 0.5 mm. The output enters magnetic separation with two parallel medium-intensity magnetic separators. The resulting concentrate is classified via hydrocyclones into two size ranges. The coarse fraction recirculates to the secondary ball mill, and the fine fraction enters a two-stage magnetic separation process using low-intensity separators.
The final concentrate is dewatered using disc filters. All tailings from the separators are sent to a scavenger magnetic separator. The scavenger tailings are split between a dewatering screen and a tailings thickener, then directed to the filtration circuit.
1.4. Concentrate Plant Phase 4
Phase 4 is a subdivision of the concentrate unit, previously known as the enrichment unit producing 0–3 mm concentrate. After modifications to the grinding circuit, it is now recognized as Phase 4. The current feed consists of ore sized 0–10 mm.
Materials are fed from under the stockpile via feeders onto conveyors leading to the primary ball mill chute. Grinding occurs with 465 kW power, reducing particle size from 6 mm to 0.5 mm. The output is classified by a primary hydrocyclone into two size fractions. The coarse fraction recirculates to the primary mill, while the fine fraction is pumped to the secondary hydrocyclone. The coarse fraction from the secondary hydrocyclone is transferred to the secondary ball mill, and the fine particles proceed to magnetic separation with two parallel low-intensity separators.
The concentrate is dewatered using a belt filter. Tailings are sent to the tailings thickener and then to the filtration circuit.
1.5. Thickeners and Filtration
The infrastructure and filtration unit includes two thickeners. One thickener permanently handles tailings from Phases 2 and 3, and temporarily from Phase 1 during critical conditions when the deep cone thickener is offline. Tailings from Phase 4 are sent to the filtration thickener if fed from standard plant feed.
A key control parameter is the solid content of the thickener feed. To enhance sedimentation rate, filtrate is added at the beginning of the circuit. Underflow with 42% solids is pumped to a buffer tank using three pumps. After homogenization, the slurry is pumped to filtration tanks, which are filled based on operational needs.
Flocculant consumption depends on preparation method, feed tonnage, and feed quality. This parameter is monitored and adjusted per shift. Due to feed quality variations, daily flocculant consumption fluctuates. Once the slurry reaches the filtration tanks, filters are activated. The facility includes eight filter presses. According to standards, the filter cake should exit with 20% moisture content.
