Abstract: The drainage water from mines in Poland has a daily contribution of, in the order of magnitude, 6,500 tons of chlorides and 0.5 ton of sulphates to the rivers Vistula (Wisla) and Oder (Odra). The largest amounts of these salts, about 78%, derive from 18 mines located mainly in the Katowice mine district. The high salt content in the water from the Vistula prevents at present its use in agriculture and causes tremendous economic losses due to corrosion attacks on pipes, machines, etc., within the industry. At present only about 4% of the river water can be classified as drinking water. To combat this problem a desalination project in Katowice has now almost been completed, including advanced treatment of wastewater for zero discharge from the two adjacent coal mines, Debiensko and Budryk. It implies elimination of 310 tons/d of salt discharge to the Odra River. The complete treatment processes are divided into three main sections: (1) pretreatment before reverse osmosis (RO) of about 12,400 m3/d drainage water from the two mines with a salinity of around 16,000 mg/l TDS on the average; (2) RO plant including post-treatment of the RO permeate; (3) a thermal plant for concentration of brine (about 4,600 m3/d) and separation of sodium chloride (NaCl) by crystallization, centrifuging and drying. The RO pretreatment includes algicide dosing in a storage tank, disinfection, flocculation/sedimentation and dual media filtration as well as granular activated carbon filtration. After a two-stage microfilter system (50 μ and 5 μ, respectively), the pretreated water is desalinated at 6-7 MPa in a RO system with spiral wound RO membranes. The RO permeate is decarbonated in a part-flow followed by addition of chemicals for disinfection and increase of the temporary hardness before distribution in the drinking water net. The flow into the thermal plant consists of the RO reject (about 2,700 m3/d) with a salinity of around 80 g/l TDS and the brine flow (about 1,870 m3/d) from the Budryk mine with about the same salinity. The first section of the thermal plant is composed of two brine concentrators, designed by Resources Conservation Company (RCC), USA. By using the seed crystal recycling technique it is possible to concentrate the feed to near the precipitation point for NaCl. The second section of the thermal plant includes one crystallizer for production of NaCl, two pusher centrifuges for salt removal from supersaturated brine and one fluidized bed dryer. The crystallizer is a forced circulation submerged-tube evaporator equipped with a mechanical vapor compressor. An additional section is also planned to be constructed for treatment of the purge from the crystallizer in order to recover other valuable chemical products and distillate. The process is fully automatic and controlled by programmable logic controllers. The plant has finally been designed by Energotechnika, Poland, after preparation of technical and economical planning of the project in coordination with Nordcap Ltd., RCC and VBB Viak-SWECO, Stockholm. In the summer 1994 the thermal plant was started up, and the RO plant is expected to be in operation during the spring 1995. The paper covers the project design with illustrations of the main parts of the plant and summarizes the results of the initial operation.

Abstract: An experimental diversion of acid mine drainage was set up near an abandoned mine in Saint Kevin Gulch, Colorado. A mass-balance approach using natural tracers was used to estimate flows into Saint Kevin Gulch. The diversion system collected about 85 percent of the mine water during its first year of operation (1994). In the first 2 months after the diversion, benthic algae in an experimental reach (stream reach around which mine drainage was diverted) became more abundant as water quality improved (increase in pH, decrease in zinc concentrations) and substrate quality changed (decrease in rate of metal hydroxide deposition). Further increases in pH to levels above 4.6, however, led to lower algal biomass in subsequent years (1995-97). An increase in deposition of aluminum precipitates at pH greater than 4.6 may account for the suppression of algal biomass. The pH in the experimental reach was lower in 1998 and algal biomass increased. Mine drainage presents a complex, interactive set of stresses on stream ecosystems. These interactions need to be considered in remediation goals and plans.

Abstract: The Henty Gold Mine, located ill Western Tasmania uses innovative solutions to effectively manage a mining operation in an environmentally sensitive setting and has been presented with several environmental awards. Fill is required as part of the mining method to provide passive ground support, minimise rock exposure and ensure maximum recovery of the small but high-grade orebody. The use of the whole portion of leach residue in the backfill reduces the surface tailing disposal requirements. Therefore, High Density Paste Fill (HDPF) has been selected as the most appropriate fill method to meet these objectives. Additional benefits include the minimisation of excess water from fill and the subsequent need for the collection and treatment of water and slimes. There are minimal equipment requirements during placement, thereby optimising mine resources for production.