Located in Mongolia, the magnetite mine is a whole industry service project contracted by Xinhai for mining, dressing and tailings industry. Through beneficiation test, it is determined that the ore is acid primary magnetite with low sulfur and low phosphorus. The main metal minerals are magnetite, hematite and limonite, in addition, quartz, but quartz has no recycling value.
Crushing and screening equipment: swinging feeder, vibrating screen, jaw crusher, cone crusher;
Grinding magnetic separation equipment: ball mill (two lattice type and two overflow type), spiral classifier, two semi counter current magnetic separators, and one magnetic pulley;
Concentrate dewatering equipment: concentrated magnetic separator, disk vacuum filter;
Tailings dewatering equipment: thickener, slurry pump, cyclone, plate and frame filter press.
The 3500t/d magnetite concentrator is divided into four workshops for beneficiation, namely crushing screening, grinding magnetic separation, concentrate dewatering and tailings dewatering. The detailed operation steps and process flow of each stage are as follows:
In the crushing stage, a three-stage one closed circuit process is adopted, and the particle size of the product is - 15mm. After the product is crushed and before entering the powder ore bin, a magnetic pulley is added to dump the waste rock in advance. The waste rock is divided into two different particle sizes, namely 0~8mm and 8~15mm. The waste rock can be sold directly.
In the grinding magnetic separation stage, the stage grinding stage magnetic separation process is adopted to avoid ore sliming caused by overgrinding, and the iron concentrate can also be separated as soon as possible.
The grid type ball mill is used for the first stage grinding, with the grinding fineness of - 200 mesh accounting for 40%. The overflow type ball mill is used for the second and third stages, with the grinding fineness of - 200 mesh accounting for 87% and - 325 mesh accounting for 95% respectively.
Semi counter current magnetic separator is adopted for magnetic separation. The magnetic field intensity of the first stage magnetic separation is 4000Oe, that of the second stage magnetic separation is 4000Oe, and that of the third stage magnetic separation is 1000Oe.
Concentrated magnetic separator is used for preliminary dehydration of magnetic concentrate, and disc vacuum filter is used for dehydration of dehydrated iron concentrate.
The first grade iron concentrate (with a grade of more than 65%) is dehydrated by disc vacuum filter, and the second grade iron concentrate (with a grade of 50%~60%) is dehydrated by disc vacuum filter.
Thickener is used to dewater magnetite tailings in the first stage; The underflow of the primary dehydration thickener is conveyed to the cyclone by slurry pump for classification;
The cyclone grit flows automatically into the dewatering screen for dehydration, and the cyclone overflow flows automatically into the two-stage thickener for concentration;
The two-stage thickener adopts the high-efficiency transformation thickener. The underflow of the two-stage thickener is transported to the filter press by slurry pump for dehydration. The overflow water of the primary and secondary thickeners is returned to the production return tank for recycling.
The above describes the process flow from beneficiation to tailings treatment of the 3500t/d magnetite concentrator, as well as the beneficiation equipment used. The final results of the project are: the grade of the first grade iron concentrate is 65.06%, the yield is 31.00%, and the recovery rate is 54.75%; The grade of the secondary iron concentrate is 51.95%, the yield is 5.00%, and the recovery is 7.05%.
