Reduction operation

Specification for Particulates Feed, recycle, and product from size reduction operations are defined in terms of the sizes involved. It is also important to have an understanding of the degree of aggregation or agglomeration that exists in the measured distribution. 

Size-reduction operation Hardness of material Size Re-diic-tion ratio 1 Tvpes of equip- ment... 

Your company receives a nickel compound (nickel compound is a listed toxic chemical category) as a bulk solid and performs various size-reduction operations (e.g., grinding) before packaging the compound in 50 pound bags. Your company processes the nickel compound. 

An overview is presented of plutonium process chemistry at Rocky Flats and of research in progress to improve plutonium processing operations or to develop new processes. Both pyrochemical and aqueous methods are used to process plutonium metal scrap, oxide, and other residues. The pyrochemical processes currently in production include electrorefining, fluorination, hydriding, molten salt extraction, calcination, and reduction operations. Aqueous processing and waste treatment methods involve nitric acid dissolution, ion exchange, solvent extraction, and precipitation techniques. 

Dissolution. Plutonium is solubilized in nitric acid solutions at Rocky Flats. The feed material consists of oxide, metal and glass, dissolution heels, incinerator ash and sand, slag, and crucible from reduction operations. The residues are contacted with 12M HNO3 containing CaF2 or HF to hasten dissolution. Following dissolution, aluminum nitrate is added to these solutions to complex the excess fluoride ion. 

Casting Skull Recycle. After ingot casting, a residue containing up to 5% of the plutonium feed remains behind. Usually the metal buttons fed to the casting operations retain some of the calcium used in the reduction operation, as well as other volatile metals and oxides. 

The major purposes of comminution or size reduction operations can be summarized in four categories as shown in Table 2.2. Comminution is almost invariably performed in two or more stages. It starts with the crude mined or quarried product this is progressively taken to the desired final size by a step-by-step process. As the process of fracture is involved throughout this procedure, a brief discussion on the fracture of materials is appropriate at this point. 

There are many variables or factors that must be considered while attempting to decide what type of equipment should be chosen for any particular size reduction operation. 

One very basic factor worth listing perhaps in the very beginning is the necessity of size reduction. It is a costly process not only in terms of money, but also in terms of energy. It may be more advantageous to buy already sized material or to alter some other stage of processing, in order to avoid the size reduction operation altogether. 

One important fact about crushers is that their working surfaces do not make contact with each other during size reduction. The size reduction operations, as has been pointed out,... 

There are many advantages in the use of chlorides as intermediates for reduction. A persistent disadvantage is that they are hygroscopic. This, when combined with the limitations associated with the use of chlorides in reduction operations designed to produce the metal in the massive form, brings forth the fluorides as more suitable intermediates. 

Beryllium is a toxic element, and the reduction operation is therefore carried out in a well-ventilated special double enclosure. The furnace controls are located outside the enclosure. The ball milling of the reduced mass is carried out in walk in-type fume hoods. 

The residues from zinc dust-acetic acid reduction operations may ignite after a long delay if discarded into waste-bins with paper. Small amounts appear to ignite more rapidly than larger portions. 

The MPT model was also reported to apply in a number other electroless metal deposition systems, including a) electroless Ni from a citrate-complexant solution with dimethylamine borane (DMAB) reductant, operated at pH = 7 (pH adjusted using NH4OH) and at a temperature (T) = 40 °C [33] b) electroless Au deposition [34] from a KAu(CN)2 containing solution, which utilized potassium borohydride... 

Accar A direct reduction ironmaking process, using coal and oil as the reductants. Operated at the OSIL plant at Keonjhar, India, from 1983 to 1987. See DR. 

Armco A direct reduction ironmaking process which used natural gas as the reductant. Operated in Houston, TX, from 1972, dismantled in 1982. See DR. 

DAV A DR ironmaking process, using coal as the reductant. Operated since 1985 at the Davsteel plant in Vanderbijlpark, South Africa. See DR. 

The apparent efficiency of the size reduction operation depends on the type of equipment used. Thus, for instance, a ball mill is rather less efficient than a drop weight type of crusher because of the ineffective collisions that take place in the ball mill. 

Thus, any representation Tcan be expressed as a function of its irreducible representations Pi. This operation is written as P = S a, Pi, where a, indicates the number of times that Pi appears in the reduction. In group theory, it is said that the reducible representation P is reduced into its Pi irreducible representations. The reduction operation is the key point for applying group theory in spectroscopy. To perform a reduction, we need to use the so-called character tables. 

The use of electrodes in aluminum reduction operations is associated with the generation of several types of wastes (Dinman 1983 IARC 1984). In aluminum reduction facilities using the prebake process, PAHs are generated. In aluminum reduction operations using the Soderberg cell process, considerable amounts of volatiles from coal tar pitch, petroleum coke, and pitch, including PAHs, are generated. 

Actions concentrating the constituents of a hazardous waste to reduce its volume. Volume reduction operations, if they simply reduce the total volume without reducing the toxicity of a waste, do not qualify as source reduction. 

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