Nodular iron production

One of today s basic requirements for economical nodular iron production is a base (or untreated) iron having between 0,004% and 0,05% sulfur. In most practices, the sulfur level is held at approximately 0,01% in order to minimize the necessary addition of nodulizing elements. On the other hand, a minimal sulfur level is evidently required in order to facilitate adequate nucleation (12). 

Dual nickel, 9 820—821 Dual-pressure processes, in nitric acid production, 17 175, 177, 179 Dual-solvent fractional extraction, 10 760 Dual Ziegler catalysts, for LLDPE production, 20 191 Dubinin-Radushkevich adsorption isotherm, 1 626, 627 Dubnium (Db), l 492t Ductile (nodular) iron, 14 522 Ductile brittle transition temperature (DBTT), 13 487 Ductile cast iron, 22 518—519 Ductile fracture, as failure mechanism, 26 983 Ductile iron... 

The Role of the Rare Earth Elements in the Production of Nodular Iron... 

Before discussing, in any detail, the role of rare earths in the production of nodular iron, it is important to arrive at some basic understanding regarding the metallurgy of this material. It is also appropriate to discuss the rare earth materials being used commercially. 

The rare earths play three roles in the production of nodular iron. These roles are as a nodulizing element (or as the growth modifier) as a means of enhancing the nodule count (or nucleation) and, finally as controllers of deleterious elements. The use of the rare earths for each of these purposes will be described in detail in the following sections. 

Similar deleterious effects of small concentrations (that is, 0.001% to 0.005%) have been well documented for bismuth and antimony. Similarly, these effects were overcome by additions of small amounts of the rare earth elements. In the industry, it is accepted that roughly 0.01% cerium (once again as mischmetal that contains 50% cerium and approximately 50% lanthanum, neodymium and praseodymium) will neutralize the effects of the deleterious elements. The result is the production of high quality nodular iron, while still allowing for the use of commercially available steel scrap as a raw material. 

The tonnages of the rare earths used are, of course, a function of the vitality of the nodular iron industry. That future looks promising indeed. In 1959, production of nodular iron castings was less than 170 thousand tons (36). By 1978, over 2.9 million tons of nodular iron castings were produced (37). 

In the mold addition process, a granular form of the alloy is placed in a small reaction chamber in the mold. The nodularizalion treatment occurs in the mold when the iron is cast, rather than in the ladle. The reaction is contained in the mold, and high recoveries result. The production of nodular iron castings is over three million tons per year. 

Linebarger H. F. et ai. The Role of the Rare Earth Elements in the Production of Nodular Iron, in Am.Chem.Soc. Symposium series 164, "Industrial Applications of the Rare Earths" ed. Gschneidner K. A., publ. 1981, 20... 

The oxidising atmosphere and relatively low flame temperature cause increased oxidation losses. This limits the possibility to feed in steel. A maximum amount of 35 % of steel is used in the production of nodular iron, though 20 % can be considered general practice. The quality of the feed needs to be well controlled since the cokeless cupola is more susceptible to bridging than the coke-fired cupola. 

In the production of nodular iron, an important advantage of the cokeless cupola is that there is no resulphurisation, so the melt may be used immediately after recarburisation. 

For the production of nodular iron, nodularisation is performed. BAT for nodularisation is to select a nodularisation technique with no ofT-gas production or to capture the produced MgO smoke, using a lid or cover equipped with extraction equipment or by using a fixed or movable hood, and to... 

A survey of the consumption and emission levels of the various technical modifications of cupola melting was set up by Neumann in 1994, as given below. All data refer to a system for the production of 10 tonne/h nodular iron with 3.6% C and 1.6% Si and at a pouring temperature of 1530 °C. The balances in Figure 10.1 show inputs, outputs and process temperatures. The latter will be higher compared to operational practice. Comparison of the various balances allows an assessment of the effect of all the modifications. 

No attempt, however, has been made to include papers concerning the numerous technical alloys (e.g., much has been said about the production of nodular iron parts using Fe-Si-R alloys), unless they revealed valuable information on phase equilibria, solid solubilities, lattice parameters or crystal-structure data. 

Alloys with other useful properties can be obtained by using yttrium as an additive. The metal can be used as a deoxidizer for vanadium and other nonferrous metals. The metal has a low cross section for nuclear capture. 90Y, one of the isotopes of yttrium, exists in equilibrium with its parent 90Sr, a product of nuclear explosions. Yttrium has been considered for use as a nodulizer for producing nodular cast iron, in which the graphite forms compact nodules instead of the usual flakes. Such iron has increased ductility. 

The largest use for calcium carbide is in the production of acetylene for oxyacetylene welding and cutting. Companies producing compressed acetylene gas are located neat user plants to minimize freight costs on the gas cylinders. Some acetylene from carbide continues to compete with acetylene from petrochemical sources on a small scale. In Canada and other countries the production of calcium cyanamide from calcium carbide continues. More recentiy calcium carbide has found increased use as a desulfurizing reagent of blast-furnace metal for the production of steel and low sulfur nodular cast iron. 

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