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Heating plants and power stations using coal as a fuel are employed worldwide as energy sources, consequently generating large quantities of fly ashes. Only a small part of these fly ashes are used as a secondary raw material. Most commonly, fly ash is deposited at sludge bed where it poses substantial ecological risks. Possibilities of utilizing fly ashes are mainly found in the construction industry; however, utilization of fly ash with a high content of unburned coal residues, expressed by loss on ignition (LOI), is limited to 2-5% LOI by the European standard STN EN 206-1. That is why fly ash with a high content of unburned coal residues is deposited at sludge bed. Fly ash deposition, hand in hand with exogenous and biogenous factors, changes the chemical and phase composition of fly ashes so the possibility for their further utilization as a secondary rawmaterial is evenmore diminished. Currently, one possibility for the use of high-LOI fly ashes is in the synthesis of geopolymers. These new materials are inorganic materials obtained from an inorganic polycondensation reaction of solid aluminosilicates with sodium silicate solution in a highly alkaline environment. This paper deals with the production of geopolymer binders from the alkaline activation of fresh and deposited fly ash. The fly ashes originated from black coal fired in melting boilers, and have a high content of unburned coal residues. Content of LOI in both fly ashes exceeds 20%. The fly ashes are alkali activated with solutions containing sodium hydroxide and sodium waterglass. The analysis examines the effects of the SiO2-to-Na2O ratio, Na2O, as well as the water content in the synthesis of fly ash-based geopolymers on their compressive strength. The compressive strength of alkali- -activated, deposited fly ash (DPA) and fresh fly ash (FFA) were 39.8MPa and 46.8MPa after 7 days, respectively. Their compressive strength increased with time. [ABSTRACT FROM AUTHOR]

The article talks about strike among black coal miners in Roslyn, Washington dealing with the racial conflict between royalty and labor class in 1888. Topics include history of Kings of Capital and Knights of Labor, approaches to settle labor disputes, and racial discrimination of African Americans. Also discussed is the economic issues faced by the blacks, American Civil War, and the role of Northern Pacific Railroad Company for filing land grants to aid construction of railroads.

Objective: The aim of the study was comparison of cancer incidence risk of lungs, stomach, colon, bladder and kidneys from ex-miners of black coal mines and the general male population of the Czech Republic. Materials and methods: The analysis was conducted in two cohorts of ex-miners according to the presence of coalworkers' pneumoconiosis (CWP). The first cohort included the miners without CWP (N = 6705), and the second cohort included the miners who were compensated for CWP (N = 2158). Personal and occupational data was merged with the data in the National Population Register and the National Oncological Register for the period from 1992 to 2006. Cancer risk in miners in comparison to the general male population of the Czech Republic was evaluated by SIR (Standardized Incidence Ratio) and 95% confidence interval (CI). Results: About twice as high risk of lung cancer was found in miners with CWP (SIR = 2.21; 95% CI: 1.75-2.76). Lung cancer risk correlated with the severity of CWP (simple CWP SIR=1.96; 95% CI: 1.48-2.56, progressive massive fibrosis SIR = 4.29; 95% CI: 2.09-7.87). No increased risk of lung cancer was found in ex-miners without CWP. The risk of malignant neoplasm at the other selected sites was comparable with the risk in the general male population of the Czech Republic. Conclusions: This study found increased lung cancer risk in coal miners with CWP, but not in those without CWP, comparing with the general population. These results served as the basis for the inclusion of lung cancer in association with CWP into a new Czech list of occupational diseases. [ABSTRACT FROM AUTHOR]