Gravity Concentration

Gravity concentration has been used throughout the ages to separate minerals, with many of the historic methods still used to the current day. With the advent of froth flotation process during the last century the significance of gravity concentration in "modern" mineral processing plants was diminished.

More recently gravity concentration has been reassessed due to the increasing costs of flotation chemicals, the relative simplic­ity of gravity processes, and the fact that they create significantly less environmental pol­lution. Because gravity separation does not require the use of chemicals, the technique offers significant advantages over many other methods of mineral concentration in meeting environmental requirements.

In many situations a large portion of the valuable mineral can at least be pre-concentrated effectively by economical and environmentally acceptable gravity systems.  The amount of reagents and energy used can be reduced considerably when the more costly methods are limited to the treatment of a gravity concen­trate. Gravity separation of minerals at coarser sizes, as soon as liberation is achieved, can boast significant advantages for down stream treatment stages due to decreased surface area, more effi­cient dewatering, and the absence of chemical coatings that can interfere with further processing.

The IPJ is an effective and efficient gravity separation device that has found application in the processing of a wide range of minerals.  Although based on the same principles as conventional jigs, its pressurised design and advanced control system give it many advantages such as high recovery, high unit throughput, low water consumption, close control of operating conditions, low installation cost, low operating costs and high security.  The IPJ can be used either in placer deposits as the primary concentrator or in hard rock circuits to treat all or part of the cyclone underflow or mill discharge.  As a result of the large combination of jig parameters and ragging types possible, the IPJ has successfully been used for a variety of minerals, including gold, sulphides, silver, native copper, tantalum, garnet and diamonds.

The IPJ is a compact, low cost continuous processing unit that requires minimal infrastructure or logistical support. As well as having a low capital cost, it has very low operating costs per tonne processed, and very low power requirements. Hutch water can be supplied from the ocean, rivers, boreholes, thickener overflow or slimes dam return. Trials using de-sliming cyclone overflow as hutch water have been conducted without any noticeable adverse effect on jig performance up to 5-6% solids w/w. The IPJ requires as little as 10% of the water consumption of traditional jigs.
 
There are currently over 200 Gekko IPJ's in operation around the World, many in Africa treating a variety of minerals, including 13 currently used in diamond applications.

The IPJ operation varies from batch centrifugal concentrators (such as the Knelson and Falcon SuperBowl) in that it produces a continuous concentrate discharge. This allows the IPJ to recover a higher portion of the feed to concentrate allowing the total re covery achievable by gravity to be optimised (Heins et al., 2003).

Benefits of Gold Gravity Circuits

• Increase in total recovery
• Reduced lock-up - gold inventory - cash flow benefit
• Minimise coarse visible gold in accessible areas such as sumps/pumps - improved security
• Reduced reagent/cyanide consumption
• Reduced Residence time
• Reduced carbon handling
• Reduced carbon wear rate
• Reduced coarse free gold levels in leach circuit
• Reduced dynamic lock-up - lower cyclone underflow grades - increased security
• Improved sampling and reconciliation

Additional Benefits of a Gekko Gravity Circuit

• The InLine Pressure Jig (IPJ) and InLine Spinner (ISP) is the right Technical Solution for this Application - refer below.
• Supported by ten-person strong met team with premium technical knowledge and skills
• Low intensity maintenance schedule and spare parts/operating cost programs
• Use of magnetic and gravity devices for pre-concentrate rather than screening - allows for greater flexibility and better performance
• Innovative, customised design specific to Beatrix's onsite design issues (eg head height)
• No pumping of gravity concentrates
• IPJ/ISP has proven recovery record in Beatrix circuit
• Technical capability to provide service and advice on a commercial basis for ongoing auditing and optimisation of circuit.
• Company owned office in RSA - not an agency relationship - committed to long term future of gold processing and African mining sector
• Low-water quality requirements
• Minimising effect of high grade slugs - IPJ acts as an absorbing buffer
• Commitment to Training
• The worlds leading intensive leach technology

 

	Gravity Concentration Intensive Leach