Purification of raw materials

The preparation conditions of each step significantly influence the physical properties and catalytic performance of the catalyst. The key steps for production of ammonia synthesis catalysts by melting method are the purification of raw materials, controlling of Fe +/Fe + ratio, and the cooling speed during the solidification process. 

Electric cable 2, Electrode with water jacket 3, Steel furnace body 4, Discharge port 5, Cooling trough with water jacket. 

Among all the materials involved in the preparation of the catalysts, the content of the refined magnetite is between 70% and 95%, which is also the major source of the silicon dioxide and harmful impurities such as sulfur. Therefore, the quality of magnetite must be strictly controlled. The chemical composition of natural magnetite is listed in Table 4.1. 

It is found that the natural magnetite is superior to the synthetic one. Very pure natural magnetite, such as Kiruna ore of Sweden, can be directly used to prepare the catalyst without refining. Natural magnetite such as Shandong ore of China usually needs to be refined via magnetic separation. 

Area Total iron Fe2+/Fe3+ FeO Si02 AI2O3 CaO MgO K2O Na20 S P2O5 Ti02  

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The anhydrous salt is prepared by several methods, eg, by reacting ZrCl with liquid anhydrous HP. It is necessary to use an excess of HP which also acts as a wetting agent. The reaction is instantaneous and is carried out in a polyethylene jar or carboy. When the evolution of HCl ceases, the material is transferred to a tray and dried under an atmosphere of nitrogen. By proper selection of equipment, purification of raw material, and drying conditions, materials of spectrographic purity can be produced (4). 

In situ purification of raw materials and catalyst reactivation can lead to... 

The importance of mass-transfer operations in chemical engineering is profound. There is scarcely any chemical process which does not require either a preliminary purification of raw materials or a final separation of products from by-products, and for these, mass-transfer operations are commonly used. Frequently, the separations constitute the major part of the costs of a process. 

The applications of surfactants in science and industry are legion, ranging from primary processes such as the recovery and purification of raw materials in the mining and petroleum industries, to enhancing the quality of finished products such as paints, cosmetics, pharmaceuticals, and foods. Table 3.2 lists some of their major areas of application. As the technological and legal demands placed on products and process additives such as surfactants increase, it seems obvious that our need to understand the relationships between the chemical structures of those materials and their physical manifestations in particular circumstances becomes more important. 

Purification of raw materials and intermediate process streams (both liquids and gases) before feeding to the reactors by separating tramp materials, undesirable impurities, pipe scales, sludge etc. 

Preparation — including purification of raw material Reaction or transformation... 

Protection of the environment from the impurities originating from industrial wastes and transportation means is a very important and current problem. Adsorbents play a significant role in neutralization of waste gases and sewages and at the same time in capturing valuable components found in wastes. Compared with other methods, adsorbents allow for the most thorough purification of raw materials with relatively low costs. 

Metal chlorides are produced either as endproducts like FeCl3, AICI3, or as intermediates for non-chlorine containing products, like titanium metal. The chlorinated intermediates allow the separation and purification of raw materials to give end products with a very high purity. 

The importance of these operations is profound. There is scarcely any chemical process which does not require a preliminary purification of raw materials or final separation of products from by-products, and for these the mass-transfer operations are usually used. One can perhaps most readily develop an immediate appreciation of the part these separations play in a processing plant by observing the large number of towers which bristle from a modern petroleum refinery, in each of which a mass-transfer separation operation takes place. Frequently the major part of the cost of a process is that for the separations. These separation or purification costs depend directly upon the ratio of final to initial concentration of the separated substances, and if this ratio is large, the product costs are large. Thus, sulfuric acid is a relatively low-priced product in part because sulfur is found naturally in a relatively pure state, whereas pure uranium is expensive because of the low concentration in which it is found in nature. 

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