A slag conditioner comprising the slag obtained from ferrochrome furnaces as a component

Abstract

The invention relates to a slag conditioner comprising the slag obtained from the ferrochrome furnaces as a component and thus enabling the production of the products with low costs and high added value.

Description

[0001] A SLAG CONDITIONER COMPRISING THE SLAG OBTAINED FROM FERROCHROME FURNACES AS A COMPONENT

[0002] TECHNICAL FIELD

[0003] The invention relates to a slag conditioner comprising the slag obtained from the ferrochrome furnaces as a component and thus enabling the production of the products with low costs and high added value.

[0004] Another aspect of the invention relates to the use of the relatively worthless slag obtained from the ferrochrome furnaces as a component in the slag conditioner production with higher added value and lower costs.

[0005] PRIOR ART

[0006] Ferrochrome is a metal compound generally used in the production of the stainless and heat-resistant steel. The ferrochrome and silicoferrochrome slag are one of the materials resulting from the processes in the electric-arc furnaces of the ferrochrome production facilities. During the production of ferrochrome and silicoferrochrome, the unreduced oxides and a part of SiOs form a slag layer on the metal surface, and this slag is removed by pouring into the molds. It is known that said slags are used as the raw materials in the applications of the base and sub-base material, earth embankment, filling, main road shoulders and hot asphalt mixtures.

[0007] The slag conditioners are generally used as the auxiliary components to obtain the technical properties expected from the slags in the production of the metals. Said “slag conditioners” have the functions of reducing the viscosity of the slag, absorbing phosphorus and sulphur and removing them from the molten metal, increasing the basicity of the slag, maintaining and regulating its fluidity, reducing the fuel consumption, ensuring less slag formation, forming less dust loss, and regulating the gas permeability of the charging material. By adding the slag conditioners, it is possible to carry out the process at lower costs and with higher efficiency. Although there are acidic and basic impurities in many ores, the acidic components (such as SiOs) are more abundant. There are also basic oxides such as CaO+MgO in the ores, but they are not available in sufficient quantities to bind the acidic SiOs. Therefore, limestone (CaCO3) is used as the flux materials in the production of the raw iron in the blast furnace in order to remove both silica and phosphorus into the slag. Limestone is a basic flux and dolomite (MgCO3.CaCO3) is an example of other basic fluxes. An example of the acidic fluxes is silica (SiOs). This flux material is generally used in the steel production. Alumina (AI2O3) is also rarely used as a flux material. It can act as acidic or basic depending on the conditions.

[0008] The slag conditioners are expected to comprise the high amounts of magnesium and silicon oxide compounds. The olivine minerals are mostly used as the slag conditioners that provide this and have relatively low costs. In particular, the slag conditioners that were widely used in the past have been replaced by the mineral olivine due to their harmful effects on the human health and environment. However, the olivine minerals have relatively high costs, causing the costs to increase in further processes.

[0009] As a result, it has become necessary to research and develop the low-cost and easily accessible new slag conditioners in order to provide the solutions and advantages to the relevant technical field needs.

[0010] SUMMARY OF THE INVENTION

[0011] It is known in the relevant technical field that the slag conditioners should consist of the oxide compounds containing the high amounts of Mg and Si. Accordingly, it is known that the compositions containing these minerals in the targeted amounts can be used as the slag conditioners. Particularly, it has been determined that the slags obtained from the ferrochrome furnaces comprise these compounds and that the present inventors can thus use said slags as the slag conditioners.

[0012] In one aspect, the invention is related to the use of the slags obtained from the ferrochrome furnaces as the slag conditioners for the storage and disposal of the slags that are harmful to the environment. An aspect of the invention relates to the use of the relatively worthless slag obtained from the ferrochrome furnaces as a component in the slag conditioner production with higher added value and lower costs.

[0013] An object of the invention is to create a new market by creating added value for the inert slag obtained from the ferrochrome furnaces.

[0014] Another object of the invention is to provide a slag conditioner that increases the melting temperature with a high amount of MgO, which allows the slag to adhere to the refractory surface and prolongs the refractory life.

[0015] Another important object of the invention is to reduce the stock amount of the slag obtained from the ferrochrome furnaces and to prevent the storage problems that may occur in the future.

[0016] DETAILED DESCRIPTION OF THE INVENTION

[0017] In this detailed description, the invention relates to a slag conditioner comprising the slag obtained from the ferrochrome furnaces as a component and thus enabling the production of the products with low costs and high added value, and is described only with the examples that will not create any limiting effect for a better understanding of the subject.

[0018] In the invention, “ferrochrome” refers to the alloys consisting of chromium and iron and containing small amounts of elements such as carbon and silicon. The ferrochrome known in the art is divided into three groups as “high, medium and low carbon ferrochrome” depending on the amount of carbon therein.

[0019] In the invention, “high carbon ferrochrome” is the most common alloy comprising 60% to 70% by weight or by mass of chromium and 4% to 6% by weight or by mass of carbon.

[0020] In the invention, the “slag conditioners” are the compositions that have the functions of reducing the viscosity of the slag, absorbing phosphorus and sulphur and removing them from the molten metal, increasing the basicity of the slag, maintaining and regulating its fluidity, reducing the fuel consumption, ensuring less slag formation, forming less dust loss, and regulating the gas permeability of the charging material.

[0021] In the relevant technical field, the ores such as dolomite and olivine are used as the slag conditioners. These and similar ores comprise high percentages of CaO, MgO, SiOs and / or AI2O3 compounds by weight. It is expected that the slag conditioners to be used instead of these ores known in the art will have at least a similar chemical composition. In particular, the slag conditioners are expected to have high amounts of MgO, AI2O3 and SiO2. Limestone (CaCO3) and dolomite (MgCO3.CaCO3) are used as the flux materials in the production of the raw iron in the blast furnace in order to remove both silica and phosphorus in the metal into the slag.

[0022] The present inventors propose the use of the slags obtained from the ferrochrome furnaces as the slag conditioners at lower costs for the relevant technical field. It has been determined that the slags obtained from said ferrochrome furnaces comprise high amounts of Mg and Si oxides as the components. Accordingly, the slags obtained from the ferrochrome furnaces suitable for use as the slag conditioners comprise at least 30% by weight of MgO and at least 20% by weight of SiO2 compounds. The slags obtained from the ferrochrome furnaces according to the invention preferably comprise a chemical composition as in Table 1 .

[0023] Table 1. Chemical composition of the slag obtained from the ferrochrome furnaces according to the invention.

[0024] When Table 1 is examined, it has been determined that the slag obtained from the ferrochrome furnaces according to the invention comprises MgO and SiO2 compounds in high weight ratios. In this way, it is clear that said slag can be used as a slag conditioner in the relevant technical field. The slag obtained from the ferrochrome furnaces absorbs the high amount of MgO compound therein and the sulfur and phosphorus in the metal, removes them from the metal and allows them to pass into the slag and changes the characteristics depending on the conditions with the AI2O3 ratio. In addition, the MgO ratio increases the melting temperature of the slag, increasing the adhesion of the slag to the refractory surface and creating a protective layer on the refractory surface.

[0025] The slags obtained from the ferrochrome furnaces according to the invention do not undergo any sizing treatment or pre-treatment in order to be used as a slag conditioner and can be used directly. In this respect, it is advantageous in terms of cost.

[0026] The chemical content of the slag obtained from the ferrochrome furnaces according to the invention is similar to the chemical content of dolomite used as flux in the iron and steel industry, and at the same time, it has a refractory protection feature compared to the flux materials known in the art, due to the high MgO content therein. In addition, since it is an inert product, it is more cost-effective than the fluxes used in the market.

[0027] On the other hand, the slag obtained from the ferrochrome furnaces has better results than the fluxes used in the industry in terms of the slag conditioner and refractory protection properties.

Claims

CLAIMS1 . A slag obtained from the ferrochrome furnaces and suitable for use as a refractory protection and slag conditioner due to the MgO and SiO2compounds therein.

2. A slag according to claim 1 , which is suitable for use as a refractory protection and slag conditioner and comprises at least 30% by weight of MgO and at least 20% by weight of SiO2compound.

3. A slag according to one of the preceding claims, which is suitable for use as a refractory protection and slag conditioner and comprises 0.1% to 0.9% by weight of C, 3% to 3.5% of Cr2O3, 35% to 40% by weight of MgO, 30% to 35% of SiO2, and 20% to 25% by weight of AI2Os.

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