The aim of the study is to determine the mercury content in hard coal, randomly taken from the USCB and in by-products of hard coal mining (fresh mining waste), i.e. aggregates (gangue) and hard coal sludge and mining waste from the Siersza dump (weathered waste). The 34 samples were intended for analysis. The total mercury content and the amount of mercury leaching from solid samples was determined. The percentage of the leaching form in the total element content, i.e. the level of mercury release from the material (leaching level), was also calculated. The amount of mercury leaching was determined by a static method using a batch test 1:10. The highest possibility of leaching mercury is characterized by weathered waste from the Siersza dump and slightly lower analyzed hard coal from the U pper Silesian Coal Basin (USCB). For hard coal samples, the total mercury content is between 0.0275–0.1236 mg/kg. However, the amount of mercury leaching from coal samples is 0.0008–0.0077 mg/kg. The aggregate is characterized by a higher total mercury content in the finest fraction 0–6 mm, within 0.1377–0.6107 mg/kg and much lower in the 80-120 mm fraction, within 0.0508–0.1274 mg/kg. The amount of elution is comparable in both fractions and amounts to 0.0008–0.0057 mg/kg. Coal sludge has a total mercury content of 0.0937–0.2047 mg/kg. L ow leaching values of 0.0014–0.0074 mg/ kg are also observed. Weathered mining waste has a total mercury content of 0.0622–0.2987 mg/kg. However, leaching values from weathered waste are much higher than from fresh mining waste. This value is 0.0058–0.0165 mg/kg. In the hard coal extracted from U SCB, the leaching level is 4.7% on average. Mining waste is characterized by a large variation in the proportion of mercury leaching form and the differences result from the seasoning time of the samples. Waste or by-products of hard coal production, such as aggregates and coal sludge, show a mercury washout form at an average level of 1.7%. The proportion of leachable form in weathered waste increased strongly to 7.3%. Elution characteristics vary for different groups of materials tested. Factors such as the type and origin of samples, their granulometric composition and the seasoning time of the material are of fundamental importance and demonstrated in the work.
In the process of extraction and enrichment of coal waste, considerable quantities of waste material are produced, mainly the gangue and coal sludge, considered as waste or raw material. The main directions of the management development of the waste rock are the production of aggregates, the production of energy products and the liquidation works in hard coal mines and the filling of excavations. The paper proposes the extension of these activities to the use of waste material. The possibility of using aggregates or extractive waste to fill open-pit excavations has been proposed, also in areas within the reach of groundwater and the possibility of building insulation layers of waste material and the production of mixtures of hard coal sludge and sewage sludge to produce material with good energy properties. The analysis was based on the author’s own research and literature data related to selected parameters of waste material. This paper presents our own preliminary studies on the amount of combustion heat and the calorific value of coal sludge combined with other wastes such as sewage sludge. The proposed methods and actions are part of the current directions of development, but they allow the extension of the scope of use of both extractive waste and products produced on the basis of gangue or coal sludge. Due to the frequent lack of the stable composition of these materials, their current properties should be assessed each time before attempting to use them. The fact that it is important to continue research to promote existing economic use and to seek new activities or methods has been concluded.
The new legislative provisions, regulating the solid fuel trade in Poland, and the resolutions of
provincial assemblies assume, inter alia, a ban on the household use of lignite fuels and solid fuels
produced with its use; this also applies to coal sludge, coal flotation concentrates, and mixtures
produced with their use. These changes will force the producers of these materials to find new
ways and methods of their development, including their modification (mixing with other products
or waste) in order to increase their attractiveness for the commercial power industry. The presented
paper focuses on the analysis of coal sludge, classified as waste (codes 01 04 12 and 01 04 81)
or as a by-product in the production of coals of different types. A preliminary analysis aimed at
presenting changes in quality parameters and based on the mixtures of hard coal sludge (PG SILESIA)
with coal dusts from lignite (pulverized lignite) (LEAG) has been carried out. The analysis
of quality parameters of the discussed mixtures included the determination of the calorific value,
ash content, volatile matter content, moisture content, heavy metal content (Cd, Tl, Hg, Sb, As, Pb,
Cr, Co, Cu, Mn, Ni, and W), and sulfur content. The preliminary analysis has shown that mixing
coal sludge with coal dust from lignite and their granulation allows a product with the desired quality
and physical parameters to be obtained, which is attractive to the commercial power industry.
Compared to coal sludge, granulates made of coal sludge and coal dust from lignite with or without
ground dolomite have a higher sulfur content (in the range of 1–1.4%). However, this is still an
acceptable content for solid fuels in the commercial power industry. Compared to the basic coal
sludge sample, the observed increase in the content of individual toxic components in the mixture
samples is small and it therefore can be concluded that the addition of coal dust from lignite or carbonates
has no significant effect on the total content of the individual elements. The calorific value
is a key parameter determining the usefulness in the power industry. The size of this parameter for
coal sludge in an as received basis is in the range of 9.4–10.6 MJ/kg. In the case of the examined
mixtures of coal sludge with coal dust from lignite, the calorific value significantly increases to
the range of 14.0–14.5 MJ/kg (as received). The obtained values increase the usefulness in the
commercial power industry while, at the same time, the requirements for the combustion of solid
fuels are met to a greater extent. A slight decrease in the calorific value is observed in the case of
granulation with the addition of CaO or carbonates. Taking the analyzed parameters into account,
it can be concluded that the prepared mixtures can be used in the combustion in units with flue gas
desulfurization plants and a nominal thermal power not less than 1 MW. At this stage of work no
cost analysis was carried out.
The trials conducted with selected chemical and biological insecticides in 1998-2000 showed the highest effectiveness of Karate Zeon 100 CS (lambda-cyhalotrine) in European corn borer (ECB) larvae control in sweet corn. The efficacy of biological insecticides containing Bacillus thuringiensis ssp. kurstaki: Biobit 3.2 WP and Lepinox WDG was very variable between the years. Reasons for insufficient efficacy of these products are discussed. The most appropriate time for the application of a chemical insecticide against ECB larvae are plant developmental stages since the beginning of pollen shedding to full blooming (63–67 BBCH scale). The efficacy of treatment was the highest at that time.
Hard coal sludge is classified as group 01 waste or it is a by-product in the production of a hard coal with variable energy importance. Pulverized lignite is not waste but a final product of drying and the very fine pulverization of lignite with a high calorific value. The study comprised the basic material before granulation such as coal sludge (PG SILESIA) and pulverized lignite (LEAG) as well as their prepared blends after the granulation on a pipe vibration granulator designed at AGH. The pulverized lignite of the LEAG company shows a low sulfur contents. In the analyzed samples its average content (Stot d) is 0.61%. An average value of this parameter in the analyzed coal sludge samples is 0.55%. The addition of pulverized lignite does not have a significant impact on the total content of sulfur and of analyzed toxic elements (Hg, As, Cd, Cr, Co, Cu, Mn, Ni, Pb, Sb, Tl, and W) in the samples. The calorific value of coal sludge falls within the range of 11.0−12.4 MJ/kg (on a dry basis). For the coal sludge and pulverized lignite blends the calorific value clearly increases to values of 14.8−17.7 MJ/kg (on dry basis). The calorific value slightly decreases in the