Gospodarka Surowcami Mineralnymi - Mineral Resources Management

The authors investigated microstructural development and selected physico-mechanical properties of the sandstones that were treated with structural strengthening chemicals. The method involved impregnation of the pore space of the rocks with various organic compounds that after polymerization at least partly cemented the grain framework. To obtain proper strengthening ofrenovated, damaged parts of the rock, the substance after polymerization should attain physico-mechanical properties approximating those in unaltered parts of the rock. The investigations were carried on the samples collected from selected outcrops of the Istebna sandstone (,,Droginia" deposit), the Godula sandstone (,,Straconka" deposit) and the Szydłowiec sandstone (,,Podkowiński" quarry). The paper presents dependences between diversified lithologies of the natural sandstones and the changes of their physico-mechanical properties resulting from application of various strengthening substances. The changes resulting from impregnation in unaltered sandstone samples allow to predict efficiency of the same strengthening processes that can be applied to various types of damaged sandstones in historic building.

In the paper the essence of the coke dry quenching process as well as the development of this technology were presented. Design projects aiming at increasing the coke throughput and the heat efficiency of the CDQ-facilities were specified. The ways of utilising the recovered heat energy, i.e. the production of process steam, electricity and gas reducers as well as preheating of the coal blend for coke production were discussed. Presented were also the causes of the wear of the component parts of a waste heat boiler and a cooling chamber. Moreover, the efforts aiming at eliminating the causes of failure standstills of the CDQ-facilities were described. Furthermore, discussed were the ways ofreducing dust and gas emission from the CDQ-facilities.

Subject of investigations was of copper sulfides such as chalcocite, bomite and chalcopyrite as well as galena. As a result of flotation investigations it has been noted that in the presence of copper sulfate all the tested minerals underwent depression though to a different degree depending on the time of flotation, amount ofCuSO4 and the time it was supplied - before or after xanthate. In the whole tested range of concentrations (50--300 g/Mg) chalcocite underwent the greatest depression regardless the time of flotation and the way of supplying the reagents. Galena underwent the least depression. Flotability of the remaining sulfides depended, to a considerable degree on the mentioned flotation parameters. Togetherwith the extension offlotation time, flotability of chalcopyrite increased and differences between the flows-off of galena and those of copper sulfides decreased. It can be concluded that the selective separation of the discussed copper sulfides from galena in the presence of copper sulfates will depend considenably on their participation in the feed given to flotation. Results ofthe elektrocinetic potential dzeta showed that both in distilledwater and in the presence ofcopper sulfate, the tested sulfides showed negative values of the potential.

In the Tarnobrzeg Sulphur District the closure and remediation of the Machów native sulphur mine is run with methods which minimize the environmental impact. In December 2002 the 25-meters-thick protection layer has been completed which sealed the bottom of the future reservoir from the polluted waters in Tertiary formations. Until the reservoir is filled with water from the Vistula River it will be drained in order to avoid the unsealing of protection layer. The mathematical model of hydrogeological conditions in the Tarnobrzeg Sulphur District and the MODFLOW software were applied to prognosing the changes in aquatic environment at the final stage of Machów open pit remediation. The results of calculations enable the optimization of draining wells location and the volume of drained Tertiary waters as well as the prediction of environmental impact of the mine closure. The modelling revealed that during the flooding of the pit the volume of waters drained from the Tertiary horizon can be substantially limited until the final closure of draining system. The new, important draining center for polluted waters from Tertiary horizon will become the unremediated open pit of the Piaseczno Sulphur Mine.

The paper presents outline of development of elementar sulfur production in Poland in the period of 1970-2002 regarding the international markets condition. The description of potential reasons of sulfur mining decline has been given. Environmental impact assessment of sulfur mining has been given as well as present state ofmines liquidation and land reclamation of post-mining areas.

Theoretical tensile strength of brittle materials is 102-104 times larger than real strength. The particle structure, apart from the force of atomic bonds in an ideal crystal, affects real strength. A single-phase particle, spatially continuous and homogenous from the point of view of its chemical composition, is assumed to be the basis. A real particle is formed by means of introducing pre-existing microcracks and other geometrical and physical internal defects. The size distribution and number ofthese defects, affecting the particle strength, form the mechanical structure ofa particle. Since both the number and size ofpre-existing microcracks are randomvariables, respectively the particle tensile strength iś°"a random variable, described by Weibull's distribution. This paper has analysed the effect of particle structure on its tensile strength from the point of view ofthe weakest link theory and the statistical theory of fracture. In both cases for the distribution is obtained whose parameters are connected with the distribution ofmicrocracks lengths (formulas 5 and 15). The next part of the paper shows the results ofempirical tensile strength tests oflimestone and porphyry particles. The authors set distribution functions of tensile strength (formulas 20-22 and figures 3-5) and calculatedWeibull's moduli of the tested samples and the average particle strength. The average particle tensile strength is connected with the particle size by one of the formulas (25), depending on the fact whether particle fracture resulted from stimulating the volume, surface or edge microcracks. In case of limestone (one-component material) the particle fracture is caused by edge microcracks (formula 27a) while for porphyry (multi-component material) by surface microcracks (formula 27b). The dependence of crushing ratio on particle strength is described by an increasing power function (formulas 29-32). The exponent in this dependence is correlated with Weibull's modulus (formula 33). The presented results concern two raw materials. Further investigations will decide whether the obtained results are of general character, concerning all materials.