Calcined product

By-products of these reactions are reclaimed and recycled. The color depends on the size of the particles formed. Size is controlled by regulating the calcination profile, ie, time and temperature. The calcined product is ground, washed, and classified. 

St. Joe Minerals Corporation uses a fluid-bed roaster to finish the roasting at 950°C of material that has been deleaded in a modified multiple-hearth furnace operated with insufficient oxidation (34). First, sulfur is reduced from 31 to 22% and lead from 0.5 to 0.013%. Somewhat aggregated, the product is hammer-milled before final roasting. Half of the calcined product is bed overflow and special hot cyclones before the boiler remove the other half total sulfur is ca 1.5%. Boiler and precipitator dusts are higher in sulfur, lead, etc, and are separated. 

Cobalt pigments are usually produced by mixing salts or oxides and calcining at temperatures of 1100—1300°C. The calcined product is then milled to a fine powder. In ceramics, the final color of the pigment maybe quite different after the clay is fired. The materials used for the production of ceramic pigments are... 

It has been found that there are several advantages to modification of pigments by addition to the calcined product of a small quantity of a dispersing agent (12). 

For best operation, the feed rate to rotating equipment should be closely controlled and uniform in quantity ana quality. Because sohds temperatures are difficult to measure and changes slowly detected, most rotating-equipment operations are controlled by indirect means. Inlet and exit gas temperatures are measured and controlled on direct-heat units such as direct dryers and kilns, steam temperature and pressure and exit-gas temperature and humidity are controlled on steam-tube units, and direct shell temperature measurements are taken on indirect calciners. Product temperature measurements are taken for secondaiy control purposes only in most instances. 

With nickel/alumina catalysts (cf. 4 ) preparation by coprecipitation or by the decomposition of a high dispersion of nickel hydroxide on fresh alumina hydrogel, yields nickel aluminate exclusively. On the other hand, when, as in impregnation, larger particles of nickel compound are deposited, the calcination product is a mixture of nickel oxide and nickel aluminate. The proportion of nickel oxide increases when occlusion of the impregnation solution leads to a very nonuniform distribution (49). 

Cobalt-on-alumina catalysts with increased dispersion and catalytic activity are prepared by addition of mannitol to the cobalt nitrate solution prior to impregnation. Thermogravimetric analysis (TGA) and in situ visible microscopy of the impregnation solution show that the organic compound reacts with cobalt nitrate, forming a foam. The foam forms because significant amounts of gas are released through a viscous liquid. The structure of the foam is retained in the final calcined product. It is this effect that is responsible for the increased dispersion. 

Nagai and Nishino [5.3] froze solutions of K2C03, Na2C03, MgS04 and A12(S04)3 18 H20 by spraying them into LN2, and freeze dried the frozen droplets at 0.13 mbar and 100 °C for 2-3 days. The dry product consisted of hollow and porous balls with a diameter from 150 to 200 pm, and had to be milled for 16 h in a ball mill to make it workable. The calcinated product had a spherical (0.1 pm diameter) or plate-like form of 0.2 to 2 pm. 

Phenols, particularly the highly chloro-or nitro-substituted variety, are an important group of organic contaminants which, at typical ambient pH, can be present in groundwater predominantly as phenolate anions. Ulibarri et al. [154] studied the adsorption capacity of 2,4,6-trinitrophenol (TNP) on Mg/Al LDHs and their calcined products. The adsorption of TNP on LDHs by anionic exchange is dramatically affected by the identity of the interlayer anion and LDH chlorides have an adsorption capacity of more than 4 times that of LDH carbonates. However, calcined LDH carbonates are more effective adsorbents than those derived by calcination of LDH chloride samples. This possibly reflects the higher surface area of the former species. 

The first is metakaolin. This is a partially calcined product that forms above about 500 °C. Only about 10% of the original hydroxyl groups of the kaohnite are retained and much of the crystalline nature of the structure is destroyed. Metakaolin is considerably more reactive than the original kaolin and appears to have an especially reactive surface. It is generally used uncoated and finds most use in plasticised PVC cable insulation, where it is reported as giving uniquely useful electrical properties [86]. 

The agreement between these two tests indicated no significant change in leach rate with time on this short time scale, for the particular elements studied ( i.e.j barium, strontium, cerium, and rare earths). It was not possible to determine the cesium content in these granules because, for economy reasons, cesium was not included in the calcine production. The results of these measurements are given in Table III. Significant differences in the leach rates of the alkaline earths (barium, strontium) the RE (europium), and cerium are observable. 

Pyrolysis of Sodium-Tetramethylammonium Zeolite Omega. Preliminary calcinations of the Q zeolites showed that intracrystalline diffusion restrictions interfered greatly with transport both of oxygen and of calcination products. Under mild conditions, coking was observed, and even under favorable conditions (550° C, thin beds, good venting) the reaction was slow. Some samples of zeolite were pyrolyzed under vacuum, and the products were identified by low resolution mass spectrometry. 

This study demonstrated that the micro-mesoporous composite materials could be synthesized with two-step treatment by microwave using two different templates system with TPABr and MTAB. This formation was controlled by the self-assembly formation of supramolecular templates between MTA micelles and SiO /TPA gels. As varying microwave irradiation time of micro-mesoporous materials, gradually transition from the mesophase to micro-mesophase was occurred. These materials have higher dm spacing of mesoporous materials and lead to transition from mesophase to micro-microphase by an increment of synthetic time, while the calcined products is formed with bimodal and trimodal pore size distribution under microwave irradiation within 3 h. From TG-DTA and PL analysis, the self-assembly formation of supramolecular templates between MTA+ micelles and SiO /TPA+ gels were monitored. 

A portion of the wet sol-intercalated clay was mixed with a surfactant of quaternary ammonium salts [CH3(CH2)n-i N(CH3)3Br] by stirring for 2 hours. 15.75 mmol of surfactant was added to each gram of the starting bentonite clay. The resultant mixture of clay and surfactant was transferred into an autoclave and kept in an oven at 100°C for 3 days. The wet cake was washed with water to Cl ions free and the solid was recovered by filtration. The solid was dried in room temperature and calcined at 773 K. for 4 h. The calcined products were labeled as sol-PILB-Cn, where n denotes the number of carbon atoms in the alkyl chain of the surfactants used. Four samples were prepared sol-PILB-C12, -C14, -C16 and -C18. 

In the process, the carbon feedstock is calcined (1250°C) to volatilize any impurities, after which the calcined products are ground, screened, weighed, mixed with binder, formed by molding or extrusion into green electrodes, and arranged in the furnace (Fig. 4). 

EUROTS-1 was synthesized (150g) by hydrothermal treatment of a gel derived from ethyl orthosilicate and ethyl orthotitanate, in the presence of tetrapropyl-ammonium hydroxide as template [31]. Each participating laboratory performed its own calcination (3 h or 16 h at a maximum temperature of 823 K, other conditions being varible). The Ti content was 2.8%, and the calcined product consisted of a single phase of orthorhombic symmetry, with a BET surface area of 435 m2g . Its IR and diffuse reflectance spectra (DRS) have been recorded. The material had the form of small rounded cubes of about 0.15/im size. 

The last claim has certainly been verified, but it has some negative aspects. The higher carbon yields are realized because the green coke fines introduced to the calciner exit as calcined product. 

At present, only two aluminum phosphate ores are known to be used for direct application after thermal treatment. One such ore is found near Thies, in Senegal. The as-mined ore contains about 29 percent P205 on a dry basis after calcination it contains over 34 percent P205. The calcined product is ground to about 95 percent smaller than 0.15 mm and marketed for direct application under the trade name Phosphal. About 75 percent of the P205 is soluble in alkaline ammonium citrate, and the product is effective as superphosphate in calcareous, neutral, and acid... 

Boehmite is itself decomposed at c. 400—450°C. As expected, the calcined products have much lower specific surface areas than the activated aluminas produced from the trihydroxides. However, the results of de Boer and his co-workers (de Boer, 1972) indicate that a sample prepared at 580°C was highly microporous and that up to this temperature there was only a small change in the external area. 

As shown in Fig. 7.7, a pure perovskite phase was obtained after calcining the milled mixture at 850°C for 4 h in air. On the other hand, a cubic pyrochlore (P3N4) phase was predominant with the coexistence of perovsWte and PbO (litharge) on the calcined products from non-milled mixture. When MgO was used instead of Mg(OH)2, no significant change of... 

Crystal growth of ZnS can be achieved by using a hydrothermal process instead of by calcination. The raw lithopone is precipitated with a slight excess of sulfide at pH 8.5. The pH is then adjusted to 12-13 with sodium hydroxide solution, and 0.5% sodium carbonate is added. The suspension is then autoclaved for ca. 15-20 min at 250-300 °C. In contrast to the wurtzite structure of the calcined product. 

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