Gold – real time ore grade measurement

SCANTECH GEOSCAN GOLD innovative sensing solution provides accurate data on gold ore feed quality at the beginning of mineral processing in real-time.

Gold mining companies now have a new capability available to help with representative grade measurement in conveyed plant feed. Elemental measurement combined with moisture and fragmentation data can provide new levels of plant control through improved ore management, early waste rejection, process improvements through reduced consumption of resources such as energy, water and reagents, and reduced fine tailings generation.

Higher and more consistent feed grades result in higher metal recoveries and increased product for the same throughput capacity generating major increases in revenue and reductions in costs. GHG emissions can be significantly reduced by processing less waste unnecessarily.

Primary crushed material on a conveyor can be representatively and continuously measured over small tonnage increments in real time using high specification prompt gamma neutron activation analysis (PGNAA). Recent advances as well as ongoing incremental improvements have resulted in Scantech GEOSCAN GOLD being used successfully on gold ores. Successful performance is already proven in many challenging bulk ore sorting applications in base metals and PGMs. Analysers are installed in gold mines in North America, Latin America, Australia, Asia and Africa. The average concentration of the Gold in the ores is 1 gram per tonne or 1 part per million.

The analyser measures a suite of elements over each 30 second increment of conveyed flow, including proxies for gold where available, as well as direct measurement of gold over 5-10 minute increments at precisions suitable for decision making (as low as 0.2 – 0.3ppm Au achieved). Decisions can be made for ore blending changes, bulk increment diversion, and feed forward control. The measurement data is also used for metal accounting and ore reconciliation.

The analyser measures elements in primary crushed rock in conveyed flows at <100 t/h to >10,000 t/h irrespective of belt speed, particle size, mineralogy, dust, moisture, or segregation/layering.

Benefits of GEOSCAN GOLD 

Higher quality measurements (e.g. precisions) enable tighter process control and improved outcomes. Customised analyser configurations and calibrations for specific applications produce the most useful, timely data possible to meet each client’s measurement requirements for effective process control.

Metal recoveries can reduce by 10% or more due to feed quality variability alone. Major gold companies are now measuring feed quality variability to develop a better understanding of its controls and consequences, and introducing systems to manage and improve it. 

Other benefits include:

• Unmatched proven performance;
• Customised calibrations;
• Operational at completion of commissioning;
• Patented non-contact design means minimal maintenance and no wear parts ;
• No sampling necessary during normal operation;
• Data directly transmitted to plant control system and owned by site;
• Proven short paybacks in a few months and sometimes weeks
• Measurement data can be used simultaneously for various applications: bulk sorting, ore blending, ore reconciliation, ore tracking, feed forward control, metal accounting, etc.
• Immediate feedback to mining operations helps confirm grade delivered against expected quality so schedules can be adjusted in real time,
• Feed forward control can be used to identify quality parameters that affect processing in real time:
• ore hardness for mill feed control,
• mineralogy and deleterious content for reagent dosing control to optimise recoveries, e.g. clays, talc, sulphides, carbonates, carbonaceous, etc.,
• sulphur content for diverting sulphide ore to flotation and oxide ore to leaching, segregating acid generating waste from clean waste, smelter feed chemistry control, etc.

Scantech is calling on all gold mining companies in Africa – and indeed, worldwide – to contact them should they require more information regarding the high performance GEOSCAN GOLD for the minerals industry.