Conditions and Design Considerations for Maximising Recoverable Gold in Roasting of Refractory Gold Ores
M G Aylmore and L W de Klerk
World Gold Conference / Brisbane, QLD, 26 - 29 SEPTEMBER 2013
ABSTRACT
Roasting of refractory gold ores has been a commercial process for many years. Improvements in design of fluidised bed roasting technologies and low capital and operating costs compared with other refractory treatment processes can potentially make roasting a viable option.
However, gold extraction from roasted ores carried out on laboratory scale equipment often invariably yields lower recoveries than other processes such as bio-oxidation or pressure oxidation. Non-optimal laboratory roasting conditions can incorrectly write roasting off as a process option.
Low gold recoveries from the cyanidation of calcine products from roasting can often be attributed to roasting conditions not favouring gold liberation and agglomeration processes, particularly if lockups of elements such as arsenic are being pursued for environmental reasons.
This paper reviews the conditions favoured for gold agglomeration and accessibility of gold to cyanide, test conditions to achieve gold liberation and agglomeration on laboratory scale and designs that incorporate staged decomposition and roasting to make roasting a more commercial option.
Improvements in hydrometallurgical uranium circuit capital and operating costs by water management and integration of utility and process energy targets
LW de Klerk[1], MP de Klerk[2], D van der Westhuizen[3]
AusImm conference - Uranium 2015
Abstract
Recovery of uranium from low grade ores often result in hydrometallurgical processing plants that operate at low uranium concentration, high volumetric flow rates and relatively large sized equipment.
Focusing on water management and integration of utility and process energy targets provides significant opportunities to reduce capital and operating costs of uranium hydrometallurgical circuits.
Using an alkaline leach uranium hydrometallurgical circuit with direct uranium precipitation as an example the effect of stream composition on the capital cost is examined. Alternatives for removal of water from the circuit are compared technically and economically.
The energy requirements for the process and utilities are examined using energy targets. The integration of the process and utility heat flows reduce energy consumption and provides energy for water removal.
The capital and operating cost savings for the circuit are quantified and are used to economically justify integrating the utility and process energy flows.
[1] Consultant, Project and Process Development, 16 Kariong Circuit, Duncraig, WA. Email louiswdeklerk@yahoo.com.au
[2] Process Engineer, Project and Process Development, 16 Kariong Circuit, Duncraig
[3] Consultant, Process Simulation and Development, 7 Armson Avenue, Magill, Adelaide