Powdered limestone

CeUulosic fibers, powdered limestone, gHsonite, and asphalt are frequently added to both water and oH muds at levels of 10 to 25 kg/m (4—10 lb /bbl) when high differential pressures are encountered to control seepage losses to the formation. This treatment also is used to improve the quaHty of the mud filter cake to reduce the chance of differential pressure sticking. 

Whereas an explosion from methane tends to be localized, it may start coal dust explosions resulting in more widespread injury and loss of life. AH coal breaking operations result in formation of fine coal particles some are controlled with water during the mining operation. Breakage associated with hauling disperses dust, and dust accumulations can be made safe by rockdusting. Powdered limestone is spread over the mine surfaces to cover the dust. 

Fire Hazards - Flash Point Not flammable but may cause fires upon contact with combustible materials Flammable Limits in Air (%) Not pertinent Fire Extinguishing Agents Flood with water, dry powder (e.g., graphite or powdered limestone) Fire Extinguishing Agents Not To Be Used Not pertinent Special Hazards of Combustion Products Not pertinent Behavior in Fire Can increase the intensity of fires Ignition Temperature Not pertinent Electrical Hazard Not pertinent Burning Rate Not pertinent. 

Fire Hazards - Flash Point Not pertinent (ignites spontaneous) Flammable limits in Air (%) Not pertinent Fire Extinguishing Agents Dry chemical, sand, powdered limestone Fire Extinguishing... 

Chemical Reactivity - Reactivity with Water No reaction Reactivity with Common Materials Corrosive to most metals with the evolution of flammable and explosive hydrogen gas Stability During Transport Stable Neutralizing AgerUs for Acids and Caustics Flush with water and apply powdered limestone, slaked lime, soda ash, or sodium bicarbonate Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

Agents for Acids and Caustics Flush with water and apply powdered limestone, slaked lime, soda ash, or sodium bicarbonate Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

FIGURE 16.40 In the basic oxygen process, a blast of oxygen and powdered limestone is used to purify molten iron by oxidizing and combining with the impurities present in it. 

The lower explosive limit and minimum explosive concentrations of flax, wool, cotton, jute, hemp and sisal fibres are of the same order of magnitude as those of highly explosive dusts [15], The explosibility of pyrites dusts with sulfur contents above 20% was evaluated experimentally. Dusts of 30% sulfur content gave explosion pressures of 3 bar at pressure rise rates of 16 bar/sec. Mixtures of 60% pyrites and 40% powdered limestone still showed significant pressure effects, and the proportion of limestone actually needed to suppress explosions was considerably above the values currently accepted by mining industries [16], Effects of mixtures of particle sizes in combustible dusts upon minimum ignition temperature (T ") and upon presence or absence of explosion were studied. Presence of 30% of fines in a coarse dust lowers Tf significantly [17], Experimental explosions of polyethylene,... 

When mixed with sodium carbonate (soda ash) and calcium carbonate (powdered limestone) and heated until the mixture melts, silica (sand) forms glass when cooled. Glass of all types has near limitless uses. One example is Pyrex, which is a special heat-resistant glass that is manufactured by adding boron oxide to the standard mixture of silica, soda ash, and limestone. Special glass used to make eyewear adds potassium oxide to the above standard mixture. 

Then the roasted ore is combined with sand, powdered limestone, and some unroasted ore (containing copper(II) sulfide), and heated at 1,100°C in a reverberatory furnace. Copper(II) sulfide is reduced to copper(I) sulfide. Calcium carbonate and silica react at this temperature to form calcium silicate, CaSiOs The liquid melt of CaSiOs dissolves iron(II) oxide forming a molten slag of mixed silicate ... 

Lithium aluminum hydride is a flammable substance. It ignites spontaneously on grinding and reacts violently with water and many organic substances. Diethyl ether, tetrahydrofuran or another suitable solvent should be used in its synthetic applications. Dry or powdered limestone is an appropriate fire extinguishing agent. 

J. Townsend patented the use of a mixture of barium carbonate and calcium oxide for converting the sulphate to carbonate. D. Hill and G. Lunge found that the reaction is complete with precipitated barium carbonate, but not with native carbonate, provided an excess of the carbonate and lime be used, the cost also is prohibitive. M. Pongowsky patented the process of converting sodium sulphate into carbonate by adding powdered limestone to an alkaline soln. of the sulphate, and treating the mixture with carbon dioxide with constant agitation. Calcium bicarbonate is formed, and this converts the sodium sulphate into carbonate. 

Incorporation of powdered limestone in Dynamite-type expls (instead of NaCl or AN) increased their disruptive force and water-resistance during storage. Different types of limestones were compared, the optimal rype having a minimum of 85% CaC03, and a maximum of 6% Si02]... 

The sensitivity of AN to initiation by heat may be increased or decreased by the presence of certain inorganic impurities. For instance, small amts of Cu increase sensitivity to heat because of the formation of a small amt of copper nitrite, which causes instability (Ref 90). The formation of Cu nitrite also was reported in Mellor, v 7 (Ref 16). Mellor also reports that the presence of Fe, Al or especially Zn in powdered form lowers the temperature required for the decompn of AN. Kast (Ref 31) reported that the presence of KMn04 in powdered form may cause the spontaneous heating of AN. Investigations conducted at Pic Arsn showed that different Cr compds such as the oxide and nitrate catalyze the decompn of AN, and in some cases explosions occurred at temps as low as 200°. Among the inorganic substances which lessen the sensitivity of AN to heat are clay, kiesel-guhr, powdered limestone etc. The same effect was expected of Amm sulfate until the disaster at Oppau in 1921 (Refs 15a 15b) rendered the safety of such a mixt uncertain. Amm sulfate had been used for many years as a desensitizer for AN in fertilizers and it was considered that such mixts could not be... 

After its subsidence, the dear liquid is decanted into another receptacle, in which it is boiled out of contact with the rnr, and stirred at the some time by some mechanical arrangement. - This ebullition expels all the volatile fatty impurities which may be present, and, consequently, the liquid loses both color and odor. As soon as the solution arrives at a density of 14s Twad-dell, it is allowed to cool, when the precipitation of a further portion of sulphate of lime occurB. Should an excess of acid be present, as may be known by its action on tincture of litmus, some chalk or powdered limestone must he added fractionally till the liquid is neutral. After this the boiling is continued as before out of contact with air, during which time the contents of tho vessel must be actively stirred, till the solution marks 37-5° Twaddcll. The sulphate and carbonate of lime are now collected on a filter, and the filtrate reduced by evaporation, till,-upon cooling, it marks 49°, care... 

Limestone consists mainly of the mineral calcite, CaC03. The carbonate content of 0.541 3 g of powdered limestone was measured by suspending the powder in water, adding 10.00 mL of 1.396 M HC1, and heating to dissolve the solid and expel COz ... 

Calcium carbonate, either powdered limestone or precipitated chalk, is used as an anti-acid in dynamite where it serves as a satisfactory stabilizer. Urea is used in dynamite and in celluloid. It reacts with nitrous acid to produce nitrogen and carbon dioxide, and is unsuitable for use in smokeless powder because the gas bubbles destroy the homogeneity of the colloid and affect the rate of burning. The small gas bubbles however commend it for use in celluloid, for they produce an appearance of whiteness and counteract the yellowing of age. 

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