Crucible furnace

Gefass-kunde, /. ceramic art. -ofen, m. (furnace containing receptacles), retort furnace, crucible furnace, pot furnace, etc. gefasst, p.p. p.a. see fassen. 

Kessel-niederscUag, m. deposit in a kettle, boiler or reservoir, -ofen, m. pot furnace crucible furnace. -rohr, n. boiler tube, -spaonung,/. boiler pressure, -speisewasser, n. boiler feed water, -speisimg, /. boiler feeding, boiler feed. 

In a muffle or crucible furnace (Fig. 11a and 6), substances are roasted in crucibles. 

Properties. Put a small amount of boron into a crucible. Put the latter into a hot crucible furnace. What happens Write the equation of the reaction. How does boron react with acids and alkalies ... 

Preparation of Vanadium(V) Oxide. Weigh 0.5 g of ammonium vanadate in a crucible. Roast the crucible with its contents up to a constant mass in a crucible furnace at 300-400 °C. Roast in an atmosphere of dry oxygen or air, feeding it into the furnace from a gas meter. Why is the substance roasted in an oxygen atmosphere Write the equation of the reaction. 

Preparation of Sodium Vanadate. Put a thoroughly triturated mixture of 0.5 g of vanadium(V) oxide and 1 g of sodium carbonate into a crucible and place it into a crucible furnace. Raise the furnace temperature to 800 °C and control the course of the process. Lower the hot crucible into a beaker with water to separate the melt easily from the crucible walls. Crush the melt in a mortar and treat it with water while heating. Evaporate the solution until crystallization begins. Examine the crystals under a microscope. Write the equation of the reaction. 

Preparation of Vanadium Oxychloride by Reacting Vanadium(V) Oxide with Thionyl Chloride. Place 16 g of ammonium vanadate into a porcelain crucible. Roast the substance up to a constant mass at 500-550 °C in a crucible furnace, passing oxygen into the latter via a glass tube from a gas meter. 

Uranium Oxides. Weigh 0.5 g of uranium peroxide hydrate in a crucible and heat it in a crucible furnace with constant stirring. 

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 ... 

The apparatus employed (Fig. 2) consists of a 500-ml. stainless-steel beaker C used in conjunction with an atmosphere chamber D equipped with gas outlets and a lid. The chamber may be constructed of 4g-in.-o.d. mild-steel pipe or from a 1500-ml. stainless-steel beaker. The gas inlet is connected to an argon (or helium) supply by means of a length of -f-in. copper tubing, coiled as shown so as to permit flexibility in handling. The best heat source is a vertical crucible furnace with 5-in. diameter chamber. (A Hoskins crucible furnace was found to be quite satisfactory.) A length of -in. stainless-steel tubing, sealed at one end, serves as a combination thermocouple well and stirrer. 

Fig. 2. Apparatus for the preparation of calcium. A, vertical crucible furnace B, stainless-steel thermocouple well C, stainless-steel reactor (500-ml. beaker) D, atmosphere chamber E, lid for atmosphere chamber F, potentiometer G, rotameter (flowmeter) II, chromel-alumel thermocouple.

Note that the apparatus in their mideighteenth-century laboratory would not be out of place in an alchemical laboratory of the Middle Ages the same range of crucibles, furnaces, and distillation apparatus (the last on the long shelf above the laboratory bench) could be found in each. 

The application of the principles of surface combustion has resulted in the development of four general types of apparatus. These forms may be described as (1) the diaphragm adaptation in which the explosive mixture bums in a porous block of refractory, Figure 21, (2) the granular bed type as used in crucible furnaces and boilers, shown in Figure 22,... 

This process is generally carried out in crucible furnaces, as adopted in England, Hungary, and other places but shaft furnaces have been used experimentally reverberatory furnaces are sometimes used, in spite of the great loss of antimony. 

Electric crucible furnaces are also obtainable. They have the advantages of a uniform and easily controlled temperature, and of easy exclusion of oxygen from the crucible chamber. However, they do not produce as high a temperature as the gas furnace, 1000°C being the usual maximum. The crucibles usually used in these furnaces... 

Basic magnesium carbonate is solidly packed into the lower half of a tall porcelain crucible. An electric crucible furnace is slowly heated. All the COg is removed within about one hour at 600°C. The still hot crucible is rapidly cooled over P gO 5 in a desiccator. The MgO is obtained as a loose, white mass which is readily soluble in dilute hydrochloric acid. 

A weighing tube is charged with 5-10 g. of the dry peroxide and placed (unstoppered) in an electric crucible furnace preheated to 350°C. A fast stream of O3 is admitted through the opening in the... 

Electrothermal atomization can be performed by graphite furnace, open filament, or vertical crucible furnace devices. Graphite furnace atomizers are the most widely used of these techniques. 

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