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The Waelz process is a method of recovering zinc and other relatively low boiling point metals from metallurgical waste (typically electric arc furnace flue dust) and other recycled materials using a rotary kiln (waelz kiln). The zinc enriched product is referred to as waelz oxide, and the reduced zinc by product as waelz slag.
These require some ingenuity of design, since the tyre must fit the shell snugly, but also allow thermal movement. The tyre rides on pairs of steel rollers, also machined to a smooth cylindrical surface, and set about half a kiln-diameter apart. The rollers must support the kiln, and allow rotation that is as nearly frictionless as possible.
The multiple hearth furnaces consist of several circular hearths or kilns superimposed on each other. Material is fed from the top and is moved by the action of rotating "rabble arms", and the revolving mechanical rabbles attached to the arms move over the surface of each hearth to continuously shift the ore.
Rotary kilns run 24 hours a day, and are typically stopped only for a few days once or twice a year for essential maintenance. One of the main maintenance works on rotary kilns is tyre and roller surface machining and grinding works which can be done while the kiln works in full operation at speeds up to 3.5 rpm.
Four Seger cones after use. Pyrometric cones are pyrometric devices that are used to gauge heatwork during the firing of ceramic materials in a kiln. The cones, often used in sets of three, are positioned in a kiln with the wares to be fired and, because the individual cones in a set soften and fall over at different temperatures, they provide a visual indication of when the wares have reached ...
Calcination is thermal treatment of a solid chemical compound (e.g. mixed carbonate ores) whereby the compound is raised to high temperature without melting under restricted supply of ambient oxygen (i.e. gaseous O 2 fraction of air), generally for the purpose of removing impurities or volatile substances and/or to incur thermal decomposition.
A rotary dryer is a type of industrial dryer used to reduce or minimize the moisture content of the material it is handling by bringing it into contact with a heated gas. [1] The dryer is made up of a rotating cylinder ("drum" or "shell"), a drive mechanism, and a support structure (commonly concrete posts or a steel frame).
The first kiln at the Coplay Cement Company was a dome kiln. Dome kilns were inefficient; they had to shut down often. In 1893 Coplay Cement built Mill B, containing the Schoefer kilns standing today. Originally enclosed in a large building, Schoefer kilns could run continuously. Soon, however, the even more efficient rotary kilns came into use.