River Ranch Diamond Mine

 diamond mine, kimberlite pipe

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Geology

The River Ranch kimberlite was discovered in 1975 whilst following up on an alluvial diamond discovered in a stream draining the kimberlite. The pipe is situated in the Central Zone of the Limpopo Belt, a zone of high grade metamorphism between the Zimbabwean and the Kaapvaal cratons and intrudes Archean metasediments of the Beitbridge Group. The kimberlite body is an east-west striking body with a fault or dyke controlled north-east trending limb extending from the western end of the main body. The surface area of the kimberlite was 5.2 ha at surface and has not lessened appreciably at the present mining level of 70m below surface. The kimberlite consists of essentially three main kimberlite types, namely tuffisitic kimberlite, tuffisitic kimberlite breccia and hypabyssal kimberlite. Also present are several donrafted blocks of sandy and crystal tuff located within the various tuffisitic kimberlite.

Mining

Run off Mine ore is reduced in size to 300mm by a 48'' X 36'' Kue Ken crusher before the washing process starts in the processing plant. RRL proudly boasts of a team of open pit mining experts managing the mining operations. Blast hole drilling is done using CHA1100s Tamrock drills. 102mm blast holes are drilled in ore to achieve reasonable fragmentation that can be handled by the Kue Ken crusher. 115mm blast holes are drilled in the waste.

Charging of blast holes is done using a Mobile Mixing Unit outsourced from Bulk Mining Explosives. HEF 100 water resistant slurry is pumped into the blast holes. The open pit has gone below the level of Limpopo River; which results in water being a challenge in the mining operations.

Production load and haul is done by a team of CAT 330 Excavators and Scania 94C Tipper trucks for both ore to the crusher and waste to waste material dumps. There is also a team of ancillary equipment dedicated to tailings and road and dump maintenance.

Diamond Mine Processes

Feed preparation

The mine plant operates two 100tph DMS/HMS modular plants for diamond recovery. These are preceded by crushing, scrubbing, screening and sizing as feed preparation. For crushing the plant incorporates a Kue Ken crusher, a Symons crusher for secondary stage crushing, and a Hazemag impactor for tertiary crushing. The secondary crusher is in closed circuit with the scrubbers. The feed to the DMS is a +1mm – 20mm.

Concentration

Concentration of the kimberlitic ore is achieved by the use of two 610mm multotec cyclones with a 160mm spigot. Suspension of 270D ferrosilicon is used as the media in the DMS circuit. The cyclones are pump fed. Tailings +1-6mm are conveyed to the tailings dump, the -1mm slimes are pumped through the thickeners to the slimes dam. The coarse floats +6mm - 20mm are recrushed using the Hazemag impactor and resend to the DMS as circulating load. Ferrosilicone and water are recycled

Diamond Recovery

The recovery consists of sizing screens, the Flow Sort X-ray machine, the grease table, the drier and the Perma Roll Separator. Concentrate delivered from the DMS to the recovery circuit is sized into four different sizes; 1-3mm, 3-6mm, 6-12mm, and 12-20mm. These are fed into the X-ray machine differently for fear of occlusion. The super concentrate from the X-ray is dried and further concentrated using the Perma Roll Magnetic Separator. The tailings from the X-ray pass through a grease table for scavenging.

Diamond Sorting

This is done on the super concentrates in a glove box.

Security

The Security is a three tier system compromising of a state of the art security system. It comprises CCTV, Access Control System and Human and Baggage X-Ray scanners. The principle of hand-off-the-product policy is followed at the Mine. All employees are duly vetted by CID before getting employment in the Mine.

Human Resources

River Ranch Limited employees over 400 people and provides accommodation to more than half of their employees and their families.

Reference for information:
www.riverranchdiamonds.com/index.php?option=com_content...