TY - THES

T1 - Crushing and Screening versus Milling in a Typical Copper Gold Plant using Current Technology

AU - Grech, Francis

N1 - embargoed until null

PY - 2011

Y1 - 2011

N2 - This report compares the efficiency, effectiveness and cost, of a typical copper/gold comminution circuit prior floatation, using current technology and best practices, to establish the most sustainable processes within the constraints of the study. The project has taken a holistic view of the above in terms of the degree of accuracy of a scoping study (Hooper 2011 slide 5). The simulations have been conducted using a fixed feed criteria in terms of material characteristics, but has captured the variables that will occur in real situations by varying the work index by ±2 kWh/t. The final product has also been fixed with the aim of producing a material grading that has 80% passing 0.15mm. Four comminution circuits have been developed to undertake this study. The options are briefly described below: Option 1 Primary gyratory crusher to a surge pile, surge pile to a SAG mill with a closed circuit pebble crusher circuit. Ball mills in closed circuit with hydrocyclones being the final stage of comminution. Option 2 Primary gyratory crusher to surge pile, surge pile to open circuit secondary screens and secondary cone crushers. This in turn is fed to a closed circuit tertiary screen and tertiary cone crusher circuit. The final stage of comminution is ball mills in a closed circuit with hydrocyclones. Option 3 Primary gyratory crusher to surge pile, surge pile to open circuit secondary screens and secondary cone crushers. This in turn is fed to a closed circuit tertiary screen and tertiary cone crusher circuit. This material is then fed to an open circuit quaternary stage comprising of vertical shaft impact crushers. The final stage of comminution is ball mills in a closed circuit with hydrocyclones. Option 4 Primary gyratory crusher to surge pile, surge pile to closed circuit secondary screens and secondary cone crushers. This in turn is fed to a closed circuit of high pressure grinding rolls and tertiary screen. The final stage of comminution is ball mills in a closed circuit with hydrocyclones. This project has shown that option 1 is the most sustainable option studied over a long term period (ie. greater than three years). This option had the highest establishment costs but the lowest operational costs. This circuit, due to the grinding circuits, also produces the highest portion of ultra fine material, while achieving a P80 in the vicinity of the target P80, effectively in total indicating that it is the most sustainable circuit. The results of options 1, 2 and 3 returned results that were very similar, certainly the majority of the results were within the accuracy of a scoping study (Hooper 2011 slide 5). Option 4 was the exception to this, as the annual operating costs, were substantially higher than the other options, as they accumulate over time, the proportional difference increases when compared to the other options. Based on this, further more conclusive studies will need to be undertaken on each of the options studied individually, with access to actual plant layouts, and structural drawings. Detailed surveys of actual equipment will need to be compiled. Each of these studies will need to be approached on a full process basis, not individual equipment, to ensure the integrity of the entire process is maintained

AB - This report compares the efficiency, effectiveness and cost, of a typical copper/gold comminution circuit prior floatation, using current technology and best practices, to establish the most sustainable processes within the constraints of the study. The project has taken a holistic view of the above in terms of the degree of accuracy of a scoping study (Hooper 2011 slide 5). The simulations have been conducted using a fixed feed criteria in terms of material characteristics, but has captured the variables that will occur in real situations by varying the work index by ±2 kWh/t. The final product has also been fixed with the aim of producing a material grading that has 80% passing 0.15mm. Four comminution circuits have been developed to undertake this study. The options are briefly described below: Option 1 Primary gyratory crusher to a surge pile, surge pile to a SAG mill with a closed circuit pebble crusher circuit. Ball mills in closed circuit with hydrocyclones being the final stage of comminution. Option 2 Primary gyratory crusher to surge pile, surge pile to open circuit secondary screens and secondary cone crushers. This in turn is fed to a closed circuit tertiary screen and tertiary cone crusher circuit. The final stage of comminution is ball mills in a closed circuit with hydrocyclones. Option 3 Primary gyratory crusher to surge pile, surge pile to open circuit secondary screens and secondary cone crushers. This in turn is fed to a closed circuit tertiary screen and tertiary cone crusher circuit. This material is then fed to an open circuit quaternary stage comprising of vertical shaft impact crushers. The final stage of comminution is ball mills in a closed circuit with hydrocyclones. Option 4 Primary gyratory crusher to surge pile, surge pile to closed circuit secondary screens and secondary cone crushers. This in turn is fed to a closed circuit of high pressure grinding rolls and tertiary screen. The final stage of comminution is ball mills in a closed circuit with hydrocyclones. This project has shown that option 1 is the most sustainable option studied over a long term period (ie. greater than three years). This option had the highest establishment costs but the lowest operational costs. This circuit, due to the grinding circuits, also produces the highest portion of ultra fine material, while achieving a P80 in the vicinity of the target P80, effectively in total indicating that it is the most sustainable circuit. The results of options 1, 2 and 3 returned results that were very similar, certainly the majority of the results were within the accuracy of a scoping study (Hooper 2011 slide 5). Option 4 was the exception to this, as the annual operating costs, were substantially higher than the other options, as they accumulate over time, the proportional difference increases when compared to the other options. Based on this, further more conclusive studies will need to be undertaken on each of the options studied individually, with access to actual plant layouts, and structural drawings. Detailed surveys of actual equipment will need to be compiled. Each of these studies will need to be approached on a full process basis, not individual equipment, to ensure the integrity of the entire process is maintained

M3 - Master's Thesis (University Course)

ER -