Metal modification

A significant practical experience of out-oven treatments have been saved up in iron manufacture; effective methods and device for a sulphur removal (desulphuration) and modifyings of fluidic pig-iron (fig.1) have been offered and realized in practice.

Ways of sulphur removal of pig-iron by submission of slag mixes on a bottom of a ladle pot, powder mixes and granules through the submersible molding box with a simultaneous blowing through neutral gas through the bottom door (a porous fuse), way of a powder wire (software) with various weighing materials' introduction are also well known. The last variant — the use of the granulated magnesium as the weighing material with inert (overwhelming pyroelectric effect) additives — is the most simple, non-poluting and rather inexpensive way. The charge of magnesium on a sulphur removal of pig-iron during such a way is about 0, 3-1 kg per 1 t of melt, depending on the initial and required contents of sulfur.

Different ways of 'late modifying' are also use for spherulitic graphite's reception (outside the oven): 'a sandwich process', 'MDS — process' (the modifying agent in a bucked kind moves to a ladle pot's bottom with the subsequent covering them with iron shaving or slabs), modifying in a jet of shielding gas, intrauniform modifying, treatment by a powder wire. Each of the specified processes has its advantages and lacks and is applied in a view of concrete conditions of manufacture. Modifying software is more widely used recently. That allows to lower pyroelectric effect, to increase «survivability» of the modifying agent and a level of its assimilation, to stabilize the graphite's structure and to improve technical and economics parameters of the process that is evidently submitted on fig. 2 and 3. At the same time such process differs relative simplicity and accuracy of a dosage. Weighing materials, made of alloys on a base of ferrosilicon with additives of calcium, barium, strontium and other active materials, are used for graphitizing treatment of pig-iron. Also the composite materials representing a mix of various components in parities, providing required characteristics of an end-product, can be used.

Parameters of a wire and technology of software input in fluidic pig-iron depend on makeup, weight, temperature of a processable material, and also on other features of concrete manufacture: type and a ladle capacity, a comparity of its height and diameter, presence of scoria and an opportunity of its disposal, time from the beginning of treatment up to a pouring-in of the last portion of fluidic metal, etc. The wire in diameter from 9 up to 16 mm and the speed of software input from 0, 5 up to 2 mm/s are usually used. The charge of software with weighing materials is approximately 0, 5-1, 5% from the weight of fluidic pig-iron, and from 0, 1 up to 0, 3% with the graphitizing weighing materials.