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The plant at the Waihi Gold Mine (WGM) in New Zealand treats Au-Ag quartz vein ore from the Martha open pit and the Correnso underground mine. The ore is processed via a conventional semi-autonomous grinding/ball circuit. A geotechnical failure at Martha in 2015 ceased open pit operations indefinitely, reducing the forecast mill tonnage. The existing process strategy had to be modified to maintain milling costs while using the existing equipment. JKSimMet software was used to develop a comminution model and a number of flow sheet variants were evaluated based on predicted throughput and efficiency. Assessments of technical risk, milling cost, operability and maintainability, grinding efficiency and overall process flexibility were carried out for different scenarios: no change, single stage SAG, no-media closed circuit SAG, low-media (4%) closed circuit SAG, and low-media (4%) open circuit SAG. Results led to the decision to reduce the SAG media charge and transition to a low throughput/high utilisation operating strategy. By the third quarter of 2015 the plant was efficiently milling 600 000 t/a at 95% utilisation, almost 40% below circuit capacity. Overall, the plant is more flexible, with throughput easily manipulated to match weekly mining rate., The plant at the Waihi Gold Mine (WGM) in New Zealand treats Au-Ag quartz vein ore from the Martha open pit and the Correnso underground mine. The ore is processed via a conventional semi-autonomous grinding/ball circuit. A geotechnical failure at Martha in 2015 ceased open pit operations indefinitely, reducing the forecast mill tonnage. The existing process strategy had to be modified to maintain milling costs while using the existing equipment. JKSimMet software was used to develop a comminution model and a number of flow sheet variants were evaluated based on predicted throughput and efficiency. Assessments of technical risk, milling cost, operability and maintainability, grinding efficiency and overall process flexibility were carried out for different scenarios: no change, single stage SAG, no-media closed circuit SAG, low-media (4%) closed circuit SAG, and low-media (4%) open circuit SAG. Results led to the decision to reduce the SAG media charge and transition to a low throughput/high utilisation operating strategy. By the third quarter of 2015 the plant was efficiently milling 600 000 t/a at 95% utilisation, almost 40% below circuit capacity. Overall, the plant is more flexible, with throughput easily manipulated to match weekly mining rate.

Selection of resistant rootstcks to overcome recent climate-change events is a crucial factor for developing sustainable agricultural practices and for assuring optimal quality of grapes.

It was proposed to use water release to dispose of excess waste water in the tailings dam, accumulated through high rainfall in the summer of 1999 at the Gympie Eldorado gold mine, Queensland. The steps involved in designing and undertaking environmentally safe water release as a model for application under the revised ANZECC (Australia New Zealand Environment and Conservation Council) 2000 water quality guidelines are described. Water analysis showed that antimony and nitrate were the likely limiting constituents for waste water release. A dilution of 1:20 was proposed, when diluted, total and WAD cyanide and arsenic are at safe levels. This dilution was shown to be safe for aquatic biota in tests using Daphnia carinata and Paratya australiensis. It was recommended that the tailings water be diluted with dewatered mine water on site and that contaminants in the mixing zone and aquatic biota in the river be monitored. Monitoring included bioassay in-stream validation. The local community were kept informed throughout the process., It was proposed to use water release to dispose of excess waste water in the tailings dam, accumulated through high rainfall in the summer of 1999 at the Gympie Eldorado gold mine, Queensland. The steps involved in designing and undertaking environmentally safe water release as a model for application under the revised ANZECC (Australia New Zealand Environment and Conservation Council) 2000 water quality guidelines are described. Water analysis showed that antimony and nitrate were the likely limiting constituents for waste water release. A dilution of 1:20 was proposed, when diluted, total and WAD cyanide and arsenic are at safe levels. This dilution was shown to be safe for aquatic biota in tests using Daphnia carinata and Paratya australiensis. It was recommended that the tailings water be diluted with dewatered mine water on site and that contaminants in the mixing zone and aquatic biota in the river be monitored. Monitoring included bioassay in-stream validation. The local community were kept informed throughout the process.