Determining phosphoric anhydride in the gaseous products in firing phosphate-bonded fireclay bodies

Conclusion A study was made of the influence of some basic technological factors on the separation of phosphoric anhydride during heat treatment of unfired chamotte refractories, containing orthophosphoric acid. On the basis of the data obtained we developed recommendations ensuring the minimum emission of phosphoric anhydride into the surroundings.Translated from Ogneupory, No. 1, pp. 17–20, January, 1993.     

Methods of eliminating expansion and embrittlement during firing of products based on chamotte from rotary furnaces

Conclusions We established the mechanism of expansion in the firing of articles made on the basis of grog obtained from rotary furnaces. The cause of the expansion is the incompleteness of the process of vitrification (sintering) during rapid heating, giving rise to the formation of closed pores. During repeat firing the expansion of the gaseous phase trapped in the closed pores gives rise to an increase in the volume of the grains.The expansion of the grog may be eliminated or substantially mitigated by breaking up the closed pores by means of an addition to the original batch of nonplastic materials or kaolins which are not prone to form expanding grog.Translated from Ogneupory, No. 4, pp. 36–41, April, 1967.     

Emission during the firing of chrome-magnesite products in tunnel kilns

Conclusions When chrome-magnesite products are fired in tunnel furnaces, the concentration in the effluent gas of dust is 110–150; of Cr₂O₃, 5–7; NO_x, 20–35; CO, 100–125; SO₂, 25–40; and SO₃, 30–70 mg/m³. The emission dust is finely dispersed. The average size of the particles of dust is 0.3, the minimum 0.05, and the maximum 1 m. There is no hydrogen sulfide, NO₂, or CrO₃ in the emission.Dust and nitrogen oxides are formed in the firing zone of the kiln. The formation of dust and NO₂ depends on the air-consumption coefficient.The use of the pipe-in-pipe type of ports does not provide good gas combustion. To improve the operation of the kiln and the combustion of the natural gas it is recommended that instead of the obsolescent tube-in-tube ports, the ports developed by the Eastern Institute of Refractories be installed since they have given good results in tests [7].To improve the scattering effect of the removal of dust in the existing equipment it is recommended that the height of the flue stacks be increased to 40–50 m.Translated from Ogneupory, No. 4, pp. 36–41, April, 1986.     

Strength properties of refractory mortar with an aluminoboro-phosphate bond during the cementing of mullite-corundum and fireclay products

Conclusions Studies were made of a refractory mortar of mullite-corundum-zircon composition with an aluminoboronphosphate bond possessing a high adhesive capacity and thermal-shock resistance. The refractory mortar can be recommended for preparing articles of block construction using blocks of corundum, mullite-corundum, and mullite compositions.Translated from Ogneupory, No. 2, pp. 15–17, February, 1988.     

Moisture expansion of ceramic tiles in double firing

The effect of chalk, slag generated at the Severstal’ Works, and Kachkanarskii slime on moisture expansion of ceramic facing tiles is investigated. It is established that chalk is the most effective in decreasing moisture expansion, slag is the next, and the weakest effect is shown by Kachkanarskii slime. __________ Translated from Steklo i Keramika, No. 1, pp. 19–20, January, 2006.     

Relationship between fluorine emission during firing of ceramic products and the firing temperature and composition of raw material

The fluorine content of clays from Lower Saxony and Bavaria was determined before and after firing. Although the mineral composition of the samples varied greatly, there was no evidence that any of the clay minerals contained significant amounts of fluorine. The amount of fluorine emitted within different temperature ranges during firing tests was determined for selected samples. Rates of temperature increase and heating times were also taken in consideration.A clear relationship between fluorine emission during firing and the Ca-content of the raw materials was demonstrated. Clays with low Ca-content started emitting fluorine at about 600°C; clays with a high Ca-content did not begin to release fluorine until 800°C. The addition of 10% CaCO₃ to a clay with a low Ca-content delayed the emission of fluorine until the higher temperature was reached.Because of the very low fluorine concentration in the raw materials, X-ray analysis could not be used to determine the compound in which calcium binds fluorine in the firing products. Tests with synthetic mixtures (NaF-CaCO₃ and NaF-CaCO₃-SiO₂) led to the conclusion that CaF₂ and various calciumfluorosilicates were involved.     

石墨制品一次焙烧废品产生原因浅析

焙烧是石墨制品生产过程中的主要热处理工序之一。焙烧生产周期较长,生坯一次焙烧质量是对压型品质量的检验,压型产生的结构问题基本上都体现在一次焙烧产品质量检查结果上,这点也证明产品一次焙烧结果和成型质量关系是比较密切的。     

Configuration of a cloud of detonation products during expansion in air

Shadowgraph techniques are used to record the configuration of detonation products in air from various kinds of high-explosive charges with spherical and cxlindrical geometries. It is established that the cloud of detonation products from a cylindrical charge after expansion to its maximum size departs considerably from a spherical configuration. The cloud of detonation products attains its ultimate size at a distance of 25–30 times the initial radius, contrary to numerical results, which indicate that this distance does not exceed 15 or 16 times the initial radius of the charge.Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 27, No. 4, pp. 121–126, July–August, 1991.