incorporate full conveyed d e p t h t r a n s m i s s i o n t e c h n o l o g i e s w h i c h provide representative results , as compared to surface based technologies which see only the top of the conveyed material .
�e COALSCAN ash and moisture monitors have been supplied to the world coal and power markets f o r o v e r 3 0 y e a r s . GEOSCAN elemental analysers are used for cement and minerals applications especially iron ore . TBM and CM100 c ondu c t ive m oisture monitors are used in many industries for moisture management . All units can be integrated with plant control systems for real time process control .
An early user of the elemental analyser technology in minerals was an iron ore mining and processing operation in South Africa . �e company used an overland conveyor to transfer crushed ore to the process plant . �e quality of the ore was variable and a need to effectively monitor its composition in real time was identi ed to allow a consistent product quality to be achieved . �e GEOSCAN analyser was installed in 2003 . �e plant was then able to respond to expected changes in ore quality before the ore arrived , and improved its performance and product quality consistency . �e experience of this installation and the improvements to the design led the company to purchase a number of analysers for its new larger plant . �is plant was designed to treat a larger range of ore types and included a series of jig circuits to upgrade the various ore types . To maximise throughput of the bene ciation plant only ore requiring bene ciation was diverted to it .
As an example of a typical copper-gold application , the need for plant feed analysis in real time was needed to improve control of copper metal units entering its processing plant due to a limited leach circuit capacity for
dissolved copper metal . �e mining operations recovered ore from several open pits where ore grade varied between less than 1 % Cu and up to 8 % Cu . Mine planning information was used to determine the expected average copper grade for each blast which was then hauled to the designated run of mine stockpile and then blended with ore from other stockpiles into a crusher and conveyed to a mill . A GEOSCAN analyser was installed on the crushed ore conveyor with the main element of interest being Cu . �e Cu content in the feed is controlled by adjusting the blend from the run of mine stockpiles approximately every 30 minutes as needed .
In a manganese application , GEOSCAN elemental analysers are used underground , for pre-sorting or the ore before it is conveyed to the surface . At the surface , the same analysers are used to ensure each delivery is produced to the end-users exact speci cation . In some applications , the difference in Mn content from one customer to the next can be 2 %, which means that it is important to have precise realtime product control over the ore quality .
Before the GEOSCAN was installed in a Zinc- Lead Concentrator Heavy Medium Plant ( HMP ), the feed was monitored via two-hourly samples collected from the HMP feed hammer autosampler and assayed on site by laboratory XRF . �ese samples had analysis turnaround times of up to eight hours . As a result of the high turnaround time , the resulting HMP feed grade data could not be used for real-time HMP process control .
Monitoring real-time variation of HMP feed grades has enabled operations personnel to make adjustments to the medium density setpoint to maintain consistent mill feed grades . Maintaining consistent mill feed grades allows stabilisation of mill operation , reducing mill power costs and mill grind size .
Finally , the monitoring of real-time variations in HMP feed grade allows operations and metallurgy personnel to provide feedback to mining on the effectiveness of ore blending strategies and dilution control . �e GEOSCAN outputs have also been used to support HMP feed hammer sampler XRF results to report grades of individual orebodies and mine sources during campaigns of speci c mine sources and ore types fed to HMP .
Return on investment for nearly all Scantech ' s analysers have been demonstrated to be in the order of a few months . Scantech provides high speci cation systems to maximise measurement accuracy and develops customised so�ware for each application .
FMDZ | Sep - Oct 2017 | Page45