Modification

Modifying and sulfur removal of pig-iron

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 practise.

 

The volume of production of castings of the total, %

 

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.

 

The degree of desulfurization of Mg in the PP flow of the initial content of sulfur in the iron

 

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.

 

The dependence of the value of the diameter of the PP desulphurization

 

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 сфередизирующими 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.

The list of weighing materials of a powder wire

for modifying and a sulphur removal of pig-iron

  • A magnesium granulated (Mg);
  • Mg + CaCO3;
  • Mg + FeSi;
  • Mg + SiCa;
  • Mg + Fe;
  • Mg + MgO;
  • Mg + FeSi + TRE ;
  • FeSiMg + TRE;
  • SiCaMg + TRE;
  • Mg + graphite, etc.