Gospodarka Surowcami Mineralnymi - Mineral Resources Management

The results of the total pore volume examination of 18 Polish bituminous coals arc presented in the paper. The research was carried out by the mercury porosimetry in connection with the mercury and helium density measurements. For the tested population of coals it was stated that there occurred a correlation between the volume of pores with the radius smaller than 7.5 nm and the mass proportion and structure of the organic matter of coal. The structure was characterised by means of a structural index simi lar to the one suggested by Oberlin. In the case of pores greater than 7.5 nm it was proved that their volume depended only on the mass proportion in coal of both of the basic components, i.e. organic and mineral matter. Moreover, it was stated that the predominant volume of pores in the examined coals was connected with the pores with radius r _< 2500 nm.

One of the essential parameters that characterizes the properties of carbonizates for use as fuels is their ignition temperature. Herein, described is a simple and fast method for the determination of the ignition temperature of solid fuels. First, discussed is a study on the selection of essential factors influencing the determination of the ignition temperature such as the mass ofsample, grain size fraction, heating rate, and oxygen flow rate. The Greek-Latin square method is applied to establish the significance of these factors. Based on the results of the study and on cost and time optimization, the following experimental values arc chosen: sample mass- 1,5 g; grain size fraction-0,5-1,0 mm; heating rate- 10 K/min; oxygen flow rate-400 cm3/min. In order to evaluate the suitability of the method, a series of measurements were carried out for ten carbonizatcs with varying degrees of carbonization and which were obtained from various hard coals. These carbonizates included, among others, typical smokeless fuels with the volatile matter contents of 8-10% which were manufactured from bituminous coals and which showed relatively high reactivities. They also included the medium reactivity cokes made by the stamping and free charging methods for other than metallurgical applications as well as a few low reactivity metallurgical cokes. The data indicated that the high reactivity smokeless fuels had the lowest ignition temperatures ranging from 350 to 400°C that should have made their combustion possible in simple grate furnaces. The ignition temperatures for the medium reactivity cokes were in the range of430-520°C and for the low reactivity metallurgical cokes were in the range of 550-590°C. The study fully confirmed the suitability of the proposed method for the determination of the ignition temperature as applied to a series of carbonizates ranging from the typical smokeless fuel with the relatively low ignition temperature of 350°C to the best quality metallurgical coke for a potential use in PCI technology with the high ignition temperature of 590°C.

Omówiono metody otrzymywania, właściwości oraz główne kierunki badań nad porowatymi materiałami węglowymi (węgiel aktywny, węglowe sita cząsteczkowe, aktywne włókniny węglowe). Wykazano przydatność adsorbentów węglowych w procesach ochrony atmosfery i wód, rozdzielania mieszanin gazowych, magazynowania paliw gazowych.

The deposits and demonstrated carbonate rocks (limestones, marbles and dolomite) resources in northern part of Vietnam are presented, as well as the possibility of their utilization in particular regions of the country, delimited by socio-economic conditions. Up to present on the terrritory ofNorth Vietnam there are 115 explored limestone deposits, 21 marble depositds and 18 deposits of dolomite. They occur mostly within Devonian, Permian-Carboniferous and Middle Triassic formations. There are 11700 mln metric tons of documented limestone resources, about 200 mln mt marble and about 3 mln mt of dolomite. They are utilized as dimmension and crushed stones, for lime and cement production (with suplementary clays as low lime component), in metallurgy, paper propduction and chemical industry and for other industrial purposcrs. The demand for carbonate row materials may be covered during the nearest 70 years by indicated resources (explored in C1 category) and during 100 years, if inferred resources (ecxplored in C2 category) are considered. The possibility of exploitation and utilization of carbonate rocks are varied in particular regions, depending of deposit size and resrerves, rock quality, geographical location, as well as geomorphological conditions, terrain accessibility and comunication network. The best conditions for industrial utilization oflimestone deposits exist in region of Red River (Devonian and Middle Triassic limestones), and less favorable in decreasing order in regions: Bak Truog Bo (Middle Triassic, Devonian and Permo--Carboniferous limestones), Dong Bak (Permo-Carboniferous and Devonian limestones) and Tay Bak (Triassic limestones).

Hitherto, the ranges of Zn-Pb orebodies have been determined on the base of Zn + Pb contents in boreholes. In general, this approach give good results, but not ever when concerning data from older drillings (frequent decrease of barren or ore minerals from drill cores). This problem could be solved by using not only contents ofmetals, but other parameters too. Because of numerous of such parameters, the methods of supervised classification i.e. the pattern recognition methods (the potential function and "Kora-J" algorithms) were used to performance the multidimensional data to one number only - the probability that particular boreholes would reveal the characteristic conditions for occurrence of orebody. To compute the probabilities in localities among existing drillings, the gcostatistical methods were used. Using the baycsian equation, these probabilities were changed into probabilities, that particular boreholes would recover an orebody. Investigations were conduct on the base of data originated from 273 boreholes, drilled in the mine area (before its foundation) and its vicinity. At first, cach drilling was described by 386 lithological, stratigraphical and tectonical features. Before classification, this number was reduced (Puri-Sen-Tamura algorithm) to 14 informative features. Though with shortness, obtained results allow one to indicate the areas of high probability of occurrence of orcbodics, Such areas, inside exhausted part of the mine, can be verified on the basis of the comparison with the borders of orcbodics. which arc proved by the exploitation. It is also possible to compare the areas with the orebodies, pointed in the standard prognosis, based on the metal content in the boreholes. The two comparisons show, that the quality of the pattern recognition method prognosis is similar to the standard prognosis. Moreover, the first prognosis delivers the new information to the second one. The information can be used as auxiliary one to better determine real distribution of orebodies. Besides, in the stage of searching for informative features, the most informative ones were found. They should reveal connections with genesis of the ore deposit, but, in this case, such interpretation was impossible.

One of the more serious problems occuring in the region of Tarnobrzeg in recent years is the liquidation of the sulphur mines Machow and Piaseczno in a manner that would minimize the threat to the natural environment. The liquidation program indicates that in place of the mining excavations recreational water reservoirs arc to be built. In the Machow excavation a 25 metre thick layer of cracovian clay is being built in order to isolate the water in the future reservoir from contaminated Tertiary waters. Since 1981, when mining activities at the Piaseczno excavations were ceased, a water reservoir has existed with the water level being maintained by directing excess water into the Vistula river. As a result of financial difficulties a isolating layer was not constructed at the Piaseczno excavation. The prognosed changes to the water quality at the Piaseczno arc based on simulation modelling results on a hydrogeological conditions model of the Tarnobrzeg Sulphur Depression. The various solutions considered the variations in the water level height at the Piaseczno reservoir and the expected proress of liquidation at the Machow mine. The basis for the hydrogeochemical balance, enabling an estimation of the water quality in the reservoir was the discharge quantity of feeder streams as well as the concentration of indicator chloride and sulphate ions. At present as well as in the prognosis, the largest contaminant load is transported into the reservoir by feeder streams filtration flows from the direction of waste disposal sites. In the final stage the concentration of the chloride ion in the reservoir waters caused by this feeder streams filtration stream flow will amount to about 42% of the total concentration while for sulphates it is about 84%. Prognostic calculations indicate that the water quality in the Piaseczno reservoir will be significantly influenced by progress and initial liquidation work relations in both post-exploitation excavations. Periodically, degradation of the water quality may occur however under the expected conditions it will improve in relation to the water quality currently observed.

Upon completion of surface sulphur mining activities in 1971, the Piaseczno mine was exploited for quartz sand in the years 1971-1980 and since then the post-exploitation workings were left in an unliquidated state. In the mine excavation a reservoir of water has formed, in which the water level is kept constant by the use of surface pumps. A 1997 mine liquidation program proposed the construction of a horizontal isolating layer and the synchronization of dewatering activities with the nearby Machów Sulphur mine at which the exploitation of sulphur has also been completed. As a result of financial and organizational decisions this program was not implemented. A realistic method for liquidating the Piaseczno works will depend upon the filling of the reservoir to a height of 146.0 m. a.s.l. and improving the surrounds. Simulation studies performed on a hydrogeological model of the Tarnobrzeg Sulphur Depression enabled the hydrodynamic effects of liquidation of the sulphur mines Machow and Piaseczno to be evaluated as they would occur during each phase of liquidation. This will to a large degree depend on the attained increase of the water level in the reservoir and the progress of liquidation works at Machów. The presented prognosis of changes to the water relations allows the description of the inflows from the Quaternary and Tertiary formations and also characterizes the expected distribution of the hydrodynamic fields. Consideration of all the possible situation development scenarios in both liquidated post-exploitation excavations showed that the immediate filling of the reservoir in Piaseczno would be beneficial. Achievement of the target water level height should be preceedcd by the implementation of a melioration system. A lack of primary and specialized drainage trenches can lead to the degradation of agricultural grounds, and for some regions can constitue a direct threat due to flooding.