Our processing facilities include:
- Five processing plants (Nos. 3, 8, 12, 14, and 16);
- Three dredges (Nos. 201, 202, and 203);
- Two stationary processing plants at alluvial mine sites (Nos. 13 and 15);
- Additional mobile processing plants.
Unloading of ore to the plant’s hopper.
Autogenous mills for wet grinding of ore at Plant No. 12.
Belt conveyor at the Plant No. 14.
Chief Classifier. Plant No. 14.
Screening Site. Plant No. 16.
Pneumatic flotationmachine. Plant No. 12.
Control panel for Plant No. 16.
At the X-ray fluorescent (XRF) separation site of
Plant No. 3.
Repair of the separator. Plant No. 3.
Plant equipment at Catoca Ltd.
Plant No. 14 of the Aikhal MPE.
As of the end of 2014, ALROSA’s mineral processing capacity totals 35.9 million tons of ore per year.
Plants 12 (Udachny MPD) and 14 (Aikhal MPD), with capacities of 12 and 10 million tons of ore per year, respectively, are the largest of their kind in ALROSA and worldwide.
Processing techniques developed by ALROSA’s engineers, do more than match the best world industry standards – they outperform them in a number of important areas.
Crucially, we use these state-of-the-art processes and equipment:
- Autogenous ore grinding in SAG and AG mills, both fabricated locally and imported (Rocksile and Svedala mills);
- locally fabricated X-ray recovery units, and conveyors of various modifications – including vertical conveyors, screens, pumps and other machinery and equipment of both Russian and foreign manufacture, allowing for comprehensive process automation.
Our process technology minimizes technogenic breakage or other damage to the diamonds to be recovered.
Our process technology and all chemicals we use are environmentally friendly, with no harmful effect.
Main Stages of Mineral Processing
1. Ore preparation (comminution and liberation)
- Crushing Section
Large rocks are reduced to smaller lumps of 0.5 m diameter and smaller;
- Head belt conveyor
This carries the reduced ore from the gyratory crusher to the feeders of the wet autogenous grinding (AG) mills. In AG mills, in a sparing mode, ore is finely ground to particles sized 0.2 mm or smaller.
We use only the best AG mills: Rocksile (made in Japan), Svedala (made in Sweden) and Syzran Engineering (made in Russia).
Diamond particles are also screened into five sizes, passing through a number of screens (GIST-72, Svedala, and others).
At the concentration stage we use equipment including XRL recovery units, jigging machines, spiral separators, flotation cells, flat-belt conveyors, and pumps.
The concentration process uses three methods:
- X-ray luminescence separation;
- Gravity concentration;
- Froth flotation.
*X-ray luminescence separation
Diamonds emit light under X-ray radiation. This light is detected by an X-ray recovery unit, which then separates the diamond-containing material from the process stream. This concentrate is sent on to the refinement section.
We use XRL recovery units of LS-20-05, LSD-20-04, and LSD-4-03 series.
*Gravity concentration (jig separation)
Diamonds are heavy minerals. This means they can be concentrated in heavy fractions using a jigging machine on a pulsating water bed. The concentrated material is then further refined.
We use jiggers of MO-318, MO-212, and MO-105 types.
*Froth flotation (or pneumoflotation)
Diamonds are hydrophobic – they repel water. So we feed slurry of the finely ground ore, water and collector chemicals into a PFM-10 M froth flotation cell. Here, small diamonds get attached to air bubbles, which rise to the surface to form froth. This froth is removed, and the concentrated mineral is further refined.
3. Final recovery, cleaning and sorting
In this concluding part of the recovery process, diamonds are:
- Recovered from the separation concentrates;
- Cleaned by treating chemicals;
- Weighed and put in containers.