Abstract: In temperate areas of abundant freshwater there is seldom an urgency to recycle. The statutory protection of inland waters for beneficial uses such as drinking, food processing and game fishing is requiring industries to choose recycling. A European success in this trend is a base metal mining/milling industry which, since 1977, is implementing hydraulic, hydrological, treatment and ecological studies with wastewaters and mine tailings. A model activity, located 50 km from Dublin is considered. Zinc and lead concentrates produced and exported to smelters ultimately yield approximately 194,000 t and 54,000 t of these respective metals (32 and 21 percent of European production). Water use as originally planned would have been approximately 6m(3)/t of ore milled. While ore milling increased by 25 percent to 8,500t/d in 1993, water use declined by 33 percent to 4m(3)/t. The components making up this reduction range from milling technology efficiency to greater recycling from the 165 ha tailings pond. Environmental standards, based on framework regulations originating in EU Directives, have been instrumental in achieving wastewater savings. A conclusion is the value of integrating water quantity, quality, recycling, storage, production and other factors early in project planning. Copyright (C) 1996 IAWQ. Published by Elsevier Science Ltd.

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: The technical knowledge and practical experience accumulated by industry and others in abating acid mine drainage (AMD) is being proactively applied at every phase of the mine life cycle. This paper traces the mine life cycle from exploration to post closure monitoring and maintenance, and reviews AMD abatement measures that have become an integral component of exploration and mining activities. Attention is increasingly being given to evaluating AMD potential as part of exploration work, and studies related to project feasibility and design. Mining, mineral processing and waste management options are selected taking into consideration their suitability to inhibit AMD. These inhibition measures are typically committed to in closure plans submitted at the permitting stage. Mines are operated and decommissioned, often progressively, as planned and in accordance with environmental protection policies. Es wird über das Problem der Säurebildung aus sulfidischen Aufbereitungsbergen und taubem Gestein im Verlauf des Existenzzyklus eines Bergwerkes berichtet. In Kanada werden seit etwa 10 Jahren intensive Forschungen für Vorhersage, Kontrolle und Eindämmung von Saürebildungen im Bergbau betrieben. Schwerpunkt ist dabei die sulfidische Oxidation (2FeS2 + 7O2 = 2FeSO4 + 2H2SO4) unter Einwirkung verschiedener physikalischer, geochemischer und biologischer Faktoren. Diese Reaktion führt zu einem Komplex weiterer chemischer Reaktionen unter Bildung von zusätzlicher Säure und Lösung von Metallen. Daraus ergeben sich zwei Hauptmöglichkeiten diesen Prozeß zu steuern: 1. die Sulfidoxidation verhindern, 2. den Oxidationsprozeß verlangsamen. Mit dem heutigen Wissensstand ist es möglich, das Säurebildungspotential von Aufbereitungsbergen zu bestimmen, den Prozeß der Sulfidoxidation von Mineralen unter bestimmten physikalischen, geochemischen und biologischen Bedingungen zu modellieren und die Säurebildung von Aufbereitungsbergen und sulfidischen Gesteinen einzudämmen. Im einzelnen werden Maßnahmen zur Bewertung des Säurebildungspotentials und zur Kontrolle und Reduzierung dieses Prozesses während der Existenzstadien Exploration, Durchführbarkeitsstudie und Genehmigung, Gewinnung und Stillegung eines Bergwerkes erläutert. An Beispielen wird gezeigt, daß bei rechtzeitgem Erkennen des Säurebildungspotentials in der Phase der Exploration Verfahren und Maßnahmen bezüglich Aufbereitung, Umgang mit Aufbereitungsbergen ausgewählt werden können.