Free Silica Content Research Articles

吸着式塵埃計に関する研究

The instrumental difference and collection efficiency of Jet Dust Counters (Roken Dust Covnter and Funken Konimeter) were studied, and the conclusions are as follows:(1) There is a significant difference between dust collecting capacity of each instrument.(2) There is an insinificant difference between 400X and 600X at a microscopic examination of dust collected on the cover glass.(3) The differences of dust kind have some significant effect on dust collection, and the humidity of atmosphere has some effect on dust collection.(4) There is an interrelation between the efficiency of dust collection and free silica content of dust.

Physico‐chemical studies on dusts. IV. Accuracy of chemical estimation of free silica in rocks and mineral dusts

AbstractThe method of Trostel & Wynne (1940) for the estimation of free silica has been applied to the analysis of coal‐measure rocks, and its suitability critically studied. If two fusions and alkali extractions are carried out, and if corrections are applied for the quartz lost during analysis, and for the presence of resistant minerals, the analytical accuracy is ± 2% in the absence of chalcedonic silica. In its presence the result is low, since the loss of chalcedonic silica during analysis is greater than that of quartz. The method cannot be used to estimate accurately the free silica content of mixtures containing both quartz and cristobalite, since the loss from cristobalite during analysis is again greater than that from quartz.

Factors Influencing Oxidation of Iron During Firing of Ground‐Coat Enamels

The oxidation of the iron beneath a ground‐coat enamel was measured by recording the progressive weight change with a sensitive balance on heating a specimen from room temperature to 1550° F. and correcting for the volatile constituents. The permeability of the dry, unfired enamel films was correlated with the variables characteristic of ground‐coat enamel slips. Clays caused the greatest change in the permeability of the unfired films; the ball clays gave lower permeability than the kaolin clays. The results showed that the permeability of the unfired coating was not an index of the amount of oxidation that occurred when the coating was fired on iron. The oxidation studies indicated that (1) a kaolin clay in an enamel slip allowed less total iron oxidation than a ball clay, since with the latter a more permeable coating developed between 900 °F. and the fusion temperature, which is believed to be due to either the organic material or the free‐silica content of the ball clay, (2) the nickel deposited on the iron by nickel flashing caused a decrease in the total amount of iron oxidation, and (3) with low‐temperature ground coats the rate of metal oxidation was the same as with conventional ground coats up to the fusion temperature of the low‐temperature enamel, but owing to the lower fusion temperature the total amount of oxidation was considerably less than with regular ground‐coat enamels.

SPALLING AND LOSS IN COMPRESSIVE STRENGTH OF FIRE BRICK1

ABSTRACTA preliminary report of the loss of compressive strength when fireclay brick from the Pacific Northwest were subjected to a series of heat treatments to 1350° and 1250°C. It illustrates some of the variations of heat treatment in the manufacturer's kilns and the differences between the high siliceous type of fire brick and the vitrifying clay type with lower free silica content. It is possible that a satisfactory spalling test may be developed in this direction.