Main trends in the theory of coal mining processes at large depths

Journal of Mining Science -     

用氮气和戊基黄药浮选时黄铁矿的低电位疏水状态

为了解释和查明N2TEC浮选法的基本原理，本文报道了在用戊基钾黄药(PAX)作捕收剂时，黄铁矿的低电位疏水状态的研究成果。新制定的N2TEC浮选法的目的是提高难处理含金硫化矿金回收率。在典型的N2TEC浮选法中，用氮气代替空气作为浮选气体，戊基钾黄药作为评选含金黄铁矿颗粒的捕收剂。l997年3月，第一个N2TEC浮选工艺在内华达州Lone Tree矿山浮选厂投产，一直操作至今。根据电化学校制接触角测量结果，研究了黄铁矿的低电位、低pH疏水状态与浮选变量(pH、气相组成、捕收剂浓度和黄铁矿电位)之间的关系。     

Minimierung der Umbauzeiten bei Stahlwerksmodernisierungen am Beispiel eines Stranggießanlagen-Umbaues

In November 2000 the Belgian stainless steel producer UGINE & ALZ Belgium nv, a company of the Arcelor Group, awarded VAI a contract for the upgrading and expansion of their steelmaking plant. The overall project included the revamping and supply of new equipment and systems for the steelmaking, continuous casting and environmental protection facilities. An essential part of this ambitious modernization program was the upgrading and expansion of the existing single-strand slab caster, with an output of 600 000 t/a, to a combined single- or twin-strand slab caster with a nominal production capacity of 1.2 million tons — the world’s largest stainless steel slab caster. All upgrading and installation activities had to be carried out within an extremely tight caster shut-down period of 21 days only in order to minimize production losses. This paper discusses the innovative project management solutions implemented in combination with extensive preassembly activities and workshop testing to assure the successful outcome of this project.     

Influence of the volume factor on the stressed state of pit flanks and unconventional technological solutions

Journal of Mining Science -     

'EUROPART'. Airborne particles in the indoor environment. A European interdisciplinary review of scientific evidence on associations between exposure to particles in buildings and health effects

The relevance of particle mass, surface area or number concentration as risk indicators for health effects in non-industrial buildings has been assessed by a European interdisciplinary group of researchers (called EUROPART) by reviewing papers identified in Medline, Toxline, and OSH. Studies dealing with dermal effects or cancer or specifically addressing environmental tobacco smoke, house dust-mite, cockroach or animal allergens, microorganisms and pesticides were excluded. A total of 70 papers were reviewed, and eight were identified for the final review: Five experimental studies involving mainly healthy subjects, two cross-sectional office studies and one longitudinal study among elderly on cardiovascular effects. From most studies, no definite conclusions could be drawn. Overall, the group concluded that there is inadequate scientific evidence that airborne, indoor particulate mass or number concentrations can be used as generally applicable risk indicators of health effects in non-industrial buildings and consequently that there is inadequate scientific evidence for establishing limit values or guidelines for particulate mass or number concentrations.     

The performance of activated sludge plants compared with the results of various bacterial toxicity tests—A study with 3,5-dichlorphenol

It was investigated whether and to what extent the results obtained by various methods of determining bacterial toxicity in waste water could be applied to conditions prevailing in activated sludge plants or in receiving water.3.5-Dichlorphenol (DCP) was studied as an example of a persistent chemical which constitutes a pollution risk to water. The bacterial toxicity limits determined by five different methods—respiration after a 20-h consumption period, consumption rate after 2-h incubation, dehydrogenase activity determined with TTC. gas formation in a fermentation tube and inhibition of the cell division of Pseudomonas—all agreed with the toxicity limit of 5 mg DCP I⁻¹ found in degradation tests in laboratory activated sludge equipment. No safety margin need be taken into account when the test results are applied to biological purification plants.In the activated sludge plants the degradation of the industrial waste water was markedly impaired only when the DCP concentration was increased to 25 mg I⁻¹. This varied in degree according to the sludge load at the beginning of the trial.Shock loads of DCP did not cause the expected fall-off in degradation but only a moderate fluctuation in its rate. The decline in degradation following continuous and also discontinuous addition of DCP was largely or completely overcome within a few weeks by the bacteria becoming adapted to DCP.In samples of river water the toxicity limit as determined by the tests was in the region of 2 mg I⁻¹.     

Treatment of gas-phase methanol in conventional biofilters packed with lava rock

The performance of laboratory scale methanol-degrading biofilters packed with lava rock was checked during almost 1 yr under different conditions. The biomass concentration and biomass adaptation of the inoculum dramatically affected the start-up and the performance of the systems during the first stages of operation. A fast start-up was obtained when using concentrated and adapted inocula, while diluted or non-adapted inocula proved to be much less efficient. The performance of the reactor during long-term operation was significantly affected by the toxic load and moisture content of the gas. Critical loads between 120 and 280 g/m(3)h were reached during different phases of the study. The reactor had a high stability to EBRT changes when working at values between 48.0 and 91.1s, showing little or no negative effect when decreasing the EBRT. Hardly any difference was observed regarding performance when using either a downflow or upflow feed, although slightly better results were obtained when working in a downflow mode.