Aluminothermic process

Niobium pentoxide also is reduced to metal commercially by the aluminothermic process. The finely ground powder is mixed with atomized aluminum and an accelerator compound which gives extra heat during reaction, then is ignited. The reaction is completed quickly and, after cooling, the slag is broken loose to free the metal derby which is purified by electron-beam melting. 

Fig. 1. Flow diagram for aluminothermic process showiag alternative methods of aluminum removal from alloy regulus.

Electrolysis. Although in Western countries the aluminothermic process has now completely replaced the electrolytic method, electrolysis is beheved to be the method used for calcium production in the People s RepubHc of China and the Commonwealth of Independent States (CIS). This process likely involves the production of a calcium—copper alloy, which is then redistilled to give calcium metal. 

Aluminothermal Method. Calcium metal is produced by high temperature vacuum reduction of calcium oxide in the aluminothermal process. This process, in which aluminum [7429-90-5] metal serves as the reducing agent, was commercialized in the 1940s. The reactions, which are thermodynamically unfavorable at temperatures below 2000°C, have been summarized as ... 

The production of metals which form very stable oxides by tire aluminothermic process, such as manganese, clrromium and vanadium is carried out with reactants at room temperature which react to provide enough heat to raise the temperature of the products to high temperatures at which the whole system is liquid. The metal phase which is produced can therefore separate from the liquid slag which is formed. The production of clrromium serves as a useful... 

The total heat requirement is thus around 599.98 kj, which is about 548.81 kj more than the heat available from the reaction. This calculation, however, does not take into account the inevitable heat losses due to the nonadiabatic conditions in the reactor. An estimate of these heat losses can be made by considering the industrial practice for aluminothermic chromium metal production. The charge is preheated to about 500 °C before loading into the aluminothermic crucible. This operation adds about 96.65 kj (i.e., 48.9 cal deg-1 475) of heat to the system. It, therefore, appears that around 41.84 kj (96.65 kj - 54.81 kj) of heat is lost due to radiation and convection for every mole of chromium sesquioxide reduced to the metal by the aluminothermic process. 

Niobium pentaoxide is used for preparing many niobium salts, including niobium carbide (Balke process). It also is used in the aluminothermic process in the production of niobium metal. 

Preparation of Iron by Aluminothermic Process. Roast iron oxide in an iron crucible (for what purpose ). Prepare a mixture of... 

Preparation of Vanadium by the Aluminothermic Process. Perform the experiment in the presence 0/ your instructor Wear eye protection or a protective mask Thoroughly dry vanadium oxide in a drying cabinet at 120-130 °C. Prepare a mixture of 10 g of vanadium(V) oxide with 6.5 g of aluminium in grains. Place the mixture into a chamotte crucible as shown in Fig. 120. 

Preparation of Manganese by the Aluminothermic Process. Perform the experiment in the presence of your instructor ) Put 20 g of finely comminuted manganese(IV) oxide into a porcelain crucible and roast it in a muffle or crucible furnace at 800 °G during an hour. What forms Why is manganese(IV) oxide not used directly for producing metallic manganese by the aluminothermic process ... 

Preparation of Potassium Permanganate by the Anode Oxidation of Manganese. Assemble an electrolyzer (see Fig. 130). Use an iron wire as the cathode and immerse it into the porous clay vessel. Take a piece of manganese produced by the aluminothermic process as the anode and fasten it in place with a thin platinum wire. Only the manganese should be submerged in the electrolyte in the anode compartment ... 

Uranium Arsenide, U3As4, may be obtained i by passing hydrogen over a fused mixture of sodium uranous chloride and sodium arsenide. It is a greyish powder which readily burns in the air. Sometimes it is obtained in a pyrophoric condition. An aluminium-containing product results when the aluminothermic process, using an oxide of uranium and arsenious oxide, is employed. The purest arsenide is obtained, in the crystalline form, when a mixture of hydrogen and arsenic vapour is passed over sodium uranium chloride. It is rapidly decomposed by nitric acid. 

The general method of producing a metai by reduction of its oxide by aluminum is called the Goldschmidt process or aluminothermic process Fig. 251.) Metallic chromium is also made by electrolytic reduction of compounds, usually chromic acid in aqueous solution. 

FIG. 25 i. The preparaiion oC a metal (in ihis case iron) by the aluminothermic process. 

Oxidation states of chromium - -2, - -3, and -f-6. Oi es of chromium chronate, FeCr204, and crocoite, PbCr04. Chromium metal and its alloys ferrochrome, alloy steels, stainless steel. The aluminothermic process (Goldschrtiidt process). Electrolytic chromium. Chromium trioxide, chromic acid, dichromic acid, potassium chromate, potassium didiromate, sodium chromate, lead chromate. Equilibrium between chromate ion and dichromate ion. Chrome-tanned leather. Chromic oxide (chrome green) chromic ion, chrome alum, chromic chloride, chromic hydroxide, chromite ion. Chromous compounds. Peroxy-chromic acid. 

Tungsten Disilicide, WSig, is obtained by heating together copper silicide and amorphous tungsten in an electric furnace. The product is washed and treated successively with nitric acid, sodium hydroxide, warm hydrofluoric acid, and water. It may also be obtained by the aluminothermic process, by ignition of a mixture containing... 

I. Strontium can be prepared by fusion electrolysis (see references for calcimn, part I), by the aluminothermic procedure (II), and by deconqiosition of azide (HI). Strontium prepared by the aluminothermic process, as well as the commercially available metal, is purified by distillation imder high vacuum. 

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