Gospodarka Surowcami Mineralnymi - Mineral Resources Management

This article analyses the relationships between the qualitative parameters of brown coal supplied to power plants. The analysis was carried out based on averaged daily data on the quality of deliveries between 2004 and 2006. The basic objective ofthe analysis has been to determine the relationships between the qualitative parameters (as received): calorific value (Q), sulphur content (S) and so-called ballast (total ash and moisture content - [A+ W]). As the analysis showed that no reliable relationship between sulphur content and the other parameters was observed. Considering the effect of this parameter would involve the potential for large errors. The most important relationships were found between the calorific value and ballast. The relationships discovered, with reference to calorific value confirm the trends that should be expected and are related to the operating properties of brown coal. Regressive calculations were made for the Q = f(A + W) and (A + W) = f(Q) dependencies, which allowed for the qualitative evaluation of how a change in some parameters affects the others. Calculations were performed for coal from individual mines and for individual years and for the entire brown coal sector. As a result ofthe calculations, equations were elaborated which, with great accuracy, depict the relationships between selected qualitative parameters.

The costs connected with utilizing secondary materials (waste) as substitute of the raw materials depend on many factors. In this paper, the emphasis is put on the functioning of the plant depending on: capital costs, ecological unit cost ofwaste recycling [zł/Mg], unit costs of processing I Mg ofwaste into secondary materials, marketing costs of the obtained product, mass fraction of the substitute obtained from the waste mass, social unit costs [zł/Mg] taking into account such aspects as creating new workplaces, etc., amount ofwork allocated for the production in fixed units, fixed costs and the amount of the processed raw material (waste). The factors will be considered in two ways: a)maximization ofthe production with the costs ofproduction fixed, b)minimization ofthe costs of production with the volume of production fixed. Much research has been done throughout the world to determine the economic and ecological profitability of secondary materials (waste) utilization in the substitution of raw materials. Unfortunately, Poland does not have sufficiently good solutions on this field. The deficiency in such solutions impedes the work of groups of specialists in various fields involved with the rational planning ofrecycling. These are the result ofourmathematical model of economic profitability of the secondary materials (waste) utilization as the substitute of primary materials, at the moment no empirical analyses have been carried out on this issue. We think that it might be a good topic for further applied studies.

Since 2000, in Poland's economy there have been considerable legal, environmental and socio-economic transitions taking place, which influence the profitability of mining companies. Favourable external factors, present in the market for raw materials in the recent years, have led to an increase in the economic efficiency of entities involved in the mining business. This phenomenon is well reflected in indices presented by GUS (the Central Statistical Office) for the entire mining sector. The present paper aims to analyse indices for individual entities in the energy and metal raw material sectors, in order to compare their profitability and operating efficiency, based on economic and financial data available in LEX-Legal and Economy Information Resource. Three basic indices have been used to assess the profitability: - return on sale (ROS), expressed as the relationship between the net profit and revenue on sales of products, goods and materials [GUS]; - return on assets (ROA) - the net profit to overall assets ratio; - return on equity (ROE), understood as the net profit in relation to the own capital. The indicative analysis of mining companies was based on data from the years 2000-2006. It was aimed at comparing the profitability and operating efficiency of individual units, and pointing out the influence of changing market conditions on their activity. Most of the companies analysed took advantage of favourable conditions in the market for raw materials, and, by so doing, improved their economic performance. The current overall ROA index for all analysed companies, proves capabilities of their property to make profits and to ensure creditworthiness (banks expect this index to be 2-6%). However, investing in the mining sector - especially in case of energy raw materials - requires also a long-term development plan to exist for that sector.

Properties of the froth layer formed in a flotation machine can affect significantly the results of coal flotation. Froth is a product of flotation where concentration of particles ofa useful component occurs. Water enters into the froth layer by surrounding both the bubbles and particles attached to the bubbles. Water content in the flotation froth is an important parameter because it affects significantly both the additional separation, taking place in the froth layer, and the amount of aqueous solution removed together with the collected particles. Therefore, the flotation froths should have a definite stability and water contents. Too much water in the froth layer removed from the flotation machine together with the collected concentrate is disadvantageous because it is an additional load for further processing operations, for example filtration. Moreover, it means also that solution and flotation reagents needed for the flotation process are being removed from the system. A low solution content in froth is unfavorable for the supplementary segregation process. The paper aims at finding a correlation between the coal flotation and water contents in the froth products. The influence of solids concentration in the pulp and flotation time on water contents in froth and coal yields was studied. Flotation tests of coal samples obtained from a jig concentrate were carried out in ca. I dm3 laboratory Denver type flotation machine. The coal samples used in the studies were the jig concentrate of hard coal fines obtained from the industrial processing plant. Low ash contents and good floatability were the characteristic features of the coal used. The influence of the solids content in the pulp and flotation time on yield of the coal concentrate and water recovery in the froth products was studied. It was observed that liquid contents in froth were proportional to the pulp volume. Moreover, it was found that there is a correlation between water content in the froth products and the concentrate yields. Highest water recovery and yield of the coal concentrates were observed for the solids contents of 80 g/dm- for all flotation times studied.

Flotacja jest procesem wzbogacania mającym na celu .zróżnicowanie zawartości składnika użytecznego w produktach rozdziału, a więc zróżnicowanie właściwości objętościowej ziarna. Wykorzystuje się do tego celu zróżnicowanie właściwości powierzchniowych ziarna. Nasuwa się więc przypuszczenie, że powinien istnieć związek pomiędzy właściwościami powierzchniowymi ziarna lub wielkościami uzależnionymi od właściwości powierzchniowych a właściwościami objętościowymi. W praktyce wzbogacania flotacyjnego przyjęło się określać rozkład właściwości flotacyjnych w próbce poprzez rozkład stałej prędkości flotacji w równaniu kinetyki I rzędu. Jeżeli flotację rozpatruje się jako proces stochastyczny narodzin i ginięcia, wtedy rozkład właściwości flotacyjnych charakteryzuje się poprzez rozkład stałej prędkości adhezji trwalej. Model narodzin i ginięcia pozwala na ilościowe określenie dwóch subprocesów zachodzących w komorze flotacyjnej, a mianowicie procesu adhezji oraz procesu odrywania już przyczepionych ziaren od pęcherzyków powietrza na skutek turbulencji ośrodka. W artykule przedstawiono omówienie modelu narodzin i ginięcia, wyspecyfikowano funkcję intensywności procesu adhezji i odrywania (wyrażenie 13), podano równanie różniczkowe modelu (wyrażenie 14) oraz jego rozwiązanie (wyrażenie 18), w którym w sposób jawny występuje stała procesu adhezji ')...0 i stała odrywania μ0• Z dopasowania empirycznej zależności uzysku składnika flotowanego od czasu flotacji do zależności modelowej otrzymuje się wartość stałej prędkości adhezji trwalej t..0• Na podstawie dyspersyjnego modelu ziarna podano wyrażenie na dystrybuantę rozkładu zawartości fazy rozproszonej (wyrażenia 21 i 22), a następnie z empirycznego związku pomiędzy stalą prędkości adhezji trwalej a zawartością popiołu (wyrażenia 3 i 4) uzyskano ogólne wyrażenie na dystrybuantę rozkładu stałej prędkości adhezji w postaci niepełnej funkcji gamma (wyrażenie 23). Badania laboratoryjne wykonano na próbce węgla (typ 33) o uziarnieniu 0,2-0,315 mm. Na podstawie analizy densymetrycznej uzyskano dystrybuantę rozkładu gęstości (wyrażenie 25 i rys. I), a za pomocą zależności pomiędzy zawartością popiołu a gęstością (wyrażenia 28 i 29 oraz rys. 2) dystrybuantę rozkładu zawartości popiołu (wyrażenie 30 i rys. 3). Badania kinetyki flotacji poszczególnych frakcji densymetrycznych wykonano z użyciembutanolu o stężeniu 2 · I0-3 mola/dmł. Krzywe kinetyki flotacji wraz z równaniami modelowymi oraz wartościami stałej prędkości adhezji trwalej przedstawiają rysunki 4--9. Zależność empiryczna stałej prędkości adhezji od zawartości popiołu jest określona przez wyrażenie (33) i rys. I O. Podstawienie zależności odwrotnej do zależności (33) do wyrażenia na dystrybuantę rozkładu zawartości popiołu (wyrażenie 30) daje ostatecznie empiryczną postać dystrybuanty rozkładu stałej prędkości adhezji trwalej (wyrażenie 35 i rys. 11) lub po zróżniczkowaniu funkcję gęstości rozkładu przedstawioną na rysunku 12. We wnioskach stwierdzono, że można wyznaczyć rozkład stałej prędkości adhezji trwalej opierając się na dyspersyjnym modelu ziarna i związku empirycznym pomiędzy stalą prędkości adhezji a zawartością popiołu. Należy w związku z tym poszukiwać teoretycznego uzasadnienia dla zastosowania tego rodzaju zależności (wzór 3) dla innych typów węgli.

Underground natural gas storage in salt caverns is the most efficient method of gas storage. Since geological and mining-engineering conditions of Polish rock-salt formations are not favourable, it is essential to specify technical parameters for each cavern independently. Stability assessment of particular cavern should include the following issues: rock salt massif strength ratio at the cavern wall, range of cavern influence and rate of cavern convergence depending on cavern loading scenario and mostly on minimal and maximal storage pressure. The paper presents analysis of the above mentioned aspects on the example of hypothetical cavern, in the case of boundary conditions, similar to typical gas storage cavern being operated in the Mogilno salt dome. The major influence on cavern stability have undefined so far rheological properties of rock salt massif, therefore in the article 4 different sets of Norton creep law parameters used in models have been analyzed. Two variants of model load, corresponding to minimal and maximal interaction of neighbouring caverns have been considered. The calculations included two kinds of cavern loading scenarios: scenario for theoretical purposes, aimed to define minimal storage pressure and scenario typical to storage cavern operation. Due to lack of explicit criteria describing long term stability of rock salt, rock salt massif strength ratio at the cavern wall was estimated on the basis of 3 independent criteria. Analysis of the calculation results showed that greater influence on stress-strain distribution of rock salt massif demonstrate creeping low, than boundary conditions. Besides, the high value of power coefficient describing stress influence in Norton creep law is not safe to estimate strain rate of rock-salt massif and cavern convergence. The calculations pointed out that micro-fracturing process in rock salt massif may occur at pressure value lower than predicted by micro-fracturing tests carried out in boreholes. Independently from the above conclusion, in the case of caverns located in homogenie part of the Mogilno salt dome, it is possible to decrease a minimal storage pressure, regardless of current technical projects. However, it is not clear that this improvement could be favourable from the point of view of effective, long-term storage capacity. Only a detailed analysis of exploitation scenario would give the answer.

The paper presents results on recognition of geological structures for CO2 storage within Mesozoic brine aquifers (Lower Cretaceous, Lower Jurassic, Lower and Upper Triassic) of Polish Lowlands. Basing on criteria issued in: The best practice for CO2 storage of in saline aquifers, 37 locations were chosen, combined with 48 structures suitable for underground carbon dioxide storage needs. Eleven ofthemcontain two reservoir horizons within the same location. Capacity calculations for chosen structures (volumetric one and dissolution based one) were executed using a unified methodology, accepted by the EU GeoCapacity project Board. Total capacity of these structures comes to 22 342 Mt (that is: volumetric 17 490 Mt, dissolution based 4852 Mt), considering capacities from several dozen up to over 2 OOO Mt of carbon dioxide. The defined capacity equals Poland's carbon dioxide emission for 70 years.

Hard coal mining industry in Poland is one of the biggest recipients of fly ashes produced by the power industry. They are used in the form of aqueous suspensions in various mining technologies on the basis of environmental and technical requirements defined in adequate regulations and standard PN/G-1 I O 11. The standard sets requirements for material samples after 28 days of seasoning. There is a lack of studies which evaluate properties of samples seasoned for a longer period of time, especially in natural conditions. The author received samples from 7 mines. The samples were excavated after a few years of staying underground. They were tested in the laboratory after adequate preparation. The test results are presented in the paper.

The paper compiles the results of laboratory tests conducted to highlight the various aspects related to CO2 sequestration in coal seams. It is therefore worthwhile to gather the information available on the interactions of CO2 with coals and the effects of CO2 on coals' properties in order to attempt a prediction of the long-term effects of sequestration. Underground storage of CO2 allows for emission reduction, awaiting the development of other sources of energy. CO2 can be stored in deep and permeable rocks isolated by overlying impermeable rock strata. In order to predict the CO2 storage capacity of a candidate coal seam and to model its long-term stability, physical properties of the coals must be known accurately. Thus, the sorption isotherms of CO2 on coal need to be treated carefully in order to obtain the desired information. The experiments were run on a low-rank coal samples (VM 33.4%)in the form of plates 15 x 15 x 5 mm. The experiments were conducted following the standard volumetric method at the temperature 298K, using the volumetric method. Tested sorbates were pure gases: CO2 and CH4 and their mixtures in variable proportions. The considered pressure range was 0--4 MPa. Sorption data and chromatographic analyses of gas mixture released during desorption reveal a clear dependence between the actual proportions of the mixture in the ampoule and the composition of desorbed gas. Low concentration of CO2 in the initial mixture causes the desorbed gas mixture to be enriched in CH4, evidencing a preferential sorption of CO2. The factor controlling the selective sorption of gases is the microstructure of coal types in the sample, as they display various porosity and swelling rate due to the presence of gases in the porous structure. Strong and specific interactions were observed between the sorbate and pores as well as stresses due to the swelling of the coal matrix, so their influence on the gas transport processes must be accounted for whilst modelling the gas storage and methane recovery operations.

Tailings produced during the manufacture of aggregates in the Rakowice sand and gravel plant (Middle Bóbr River valley, SW Poland) were characterized in the paper. A 3.0 inches laboratory Knelson concentrator was used to evaluate the recovery of free gold from tailings collected from the sand and gravel processing plant. Gravity recoverable gold (GRG) was determined using the difference between the gold content in the Knelson feed and the tails. Analysis of several samples collected from different types of tailings revealed the average content of 0.27 ppm of gold and recoveries ofgold between 85-98% in the concentrates. The sand and gravel deposits are thus potential sources of gold and other economic heavy minerals, mainly of ilmenite and titanomagnetite, as well as small amounts of zircon, monazite and rutile. The annual deposition of about 6 kg of Au and 1000 Mg of other heavy minerals in the tailing pond during the last 5 years of the Rakowice Mine operation has been assessed.