A. V. Gulyaeva

More Durable Lining for Horizontal Copper-Nickel Converters

Results are presented from a study of the durability of the lining of horizontal converters and the reasons for the short service life of the lining’s tuyere zone. The article describes new designs of tuyere-zone linings and new tuyere blocks developed on the basis of the study results. Technologies have been developed for making periclase-chromite tuyere blocks and a heat-conducting bulk refractory which is resistant to slag-matte melts. The blocks are made using a fused material that has a high content of Cr2O3. The durable new lining was tested and introduced on converters at the Alaverdinsk Mining-Metallurgical Combine and Ufalei Nickel Plant. The new linings last 1.5 – 2.0 times longer than the linings used previously.

Effective Highly Resistant Waelz Kiln Linings

Conditions are analyzed for service of Waelz kiln linings of the Chelyabinsk Electrolytic Zinc Plant and the Ust’-Kamenogorsk Lead and Zinc Combine, and the main reasons for refractory wear are revealed. Refractory grades PKhPP and KhPT are most resistant for service conditions in Waelz kiln linings. In order to improve Waelz kiln lining life chromite-periclase heat-resistant refractory lining schemes are developed and introduced, a high-temperature adhesive is developed, impregnation of refractories with coal-tar pitch is accomplished, and a test batch of objects is prepared and tested in a Waelz kiln lining. A laying mortar based on self-propagating high-temperature synthesis is developed. Spatial geometric shapes, optimum dimensions, ceramic object structure, and layups based on them are studied. Linings are tested in theWaelz kilns of a number of enterprises.

Durable Linings for the Tap Holes of Ore-Roasting Furnaces

The reasons for the short service life of the lining of the tap holes in ore-roasting furnaces at nickel and tin factories are analyzed. It is established that the main reasons are the large number of seams in the lining and the low resistance of the sintered periclase-chromite refractories to slag and abrasion.Work has been done to create a seamless design of tap hole made of a slag-resistant refractory. Blocks made of PShFB-grade refractories have been developed along with a fused periclase-chromite refractory (grade PKhPP) and a new high-temperature adhesive. Use of the seamless tap holes has increased the life of their lining by a factor of 2.0 – 2.5.

Fused Magnesia-Based Refractories with Improved Heat Resistance

The introduction of various additions into fused magnesia-based refractories is studied in order to make these products more heat-resistant and reduce the cost of producing high-performance refractories. The study results are used to attempt to improve the heat-resistance of refractories through the addition of Cr2O3 However, the formation of ferrochromium during the refining operation lowers the refractories’ service temperature. The optimum addition turns out to be 5 – 15% unfired magnesite MgCO3. Refractory products with improved heatresistance can be effectively used in the linings of high-temperature equipment employed in ferrous and nonferrousmetallurgy, including fluidized-bed furnaces, Kivtset-TsS furnaces, horizontal converters, ore-roastingfurnaces, vertical converters, and electric furnaces used in ferrous metallurgy.

Increased Life for Open-Hearth Furnace Roof Lining

Reasons are studied for the short life of sprung-suspended roofs of open-hearth furnaces and refractory objects are developed with reduced thermal conductivity and a special hook. During refractory laying a shrinkage-free high-temperature laying mortar is used. OAO Nizhnyi Tagil’ Metallurgical Combine organizes industrial output of the refractories developed. Industrial testing is carried out in open-hearth furnace arched roofs of OAO Nizhnyi Tagil’ Metallurgical Combine (NTMK) and ZAO Nizhnyi Sergi Metalware and Metallurgical Plant (NMMZ). According to test results the increase in roof life is 20 – 30%, and the economic effect for two open-hearth furnaces is 4,656 million rubles per year.

Efficient Lining for Steel-Pouring Ladles

An analysis was made of the reasons for the short service life of the lining of steel-pouring ladles and malfunctions of fountains used for bottom-pouring. A high-temperature adhesive was developed and the most chemically stable refractory materials were chosen for it. The operating regime of steel-pouring ladles in the open-hearth shop at the Revda Hardware-Metallurgical Plant (in Revda) was studied, and based on the study results the shop replaced its fireclay bricks with MKRAP refractories. The authors used those results to also develop a mortar that has increased the life of the lining 30 − 50%. Use of the highly stable high-temperature adhesive in fountains has reduced metal loss during bottom-pouring operations.

A Study of 3D Geometric Shapes, Optimum dimensions, and Designs for Refractory Products for Improved Unit Durability

We have developed, tested, and installed tuyere blocks that reduce by a factor of 9 the number of joints in horizontal-converter tuyere belts, decrease corrosive wear on the refractory products, and reduce the likelihood of penetration by slag-matte melt. A design was developed for a special refractory product that reduces thermal stress as well as heating time, prevents the products from falling from brick courses in roofs, and sharply diminish thermal losses through the brickwork in open-hearth furnaces as well as ore-roasting furnaces and through the lining in Waelz kilns. These special-design products enabled improvements to the lining performance of the high-temperature units without increasing maintenance costs.

Creation of High-Efficiency Promising Refractory Materials and Constructions for the Lining of Metallurgical Units

The causes of the low level of stability of the tuyere zone of converters and the reaction zone of rotating furnaces are studied and methods of impregnating standard refractories with different binding agents and effective refractory bodies, glues, gunning bodies, and constructions of linings are developed. A construction of a plant for the fabrication of gunning bodies is proposed. On the basis of tests and the introduction of these measures, the stability of the lining of converters and rotating furnaces can be increased 1.5 – 2-fold at nonferrous metallurgical enterprises and the number of repairs and volume of losses of nonferrous metals reduced.

Fused Refractory Oxides Increasing Nonferrous Metallurgy Unit Lining Life

Technology is developed for preparing periclase-chromite composition refractories based on fused grains of increased thermal-shock resistance. Technology is created for preparing periclase composition refractories based on fused grains exhibiting a high service temperature (up to 1900°C) and improved thermal shock resistance. Refractory material SHS-technology is developed on whose basis fused refractory objects, brickwork mortars, and torcrete mixes for hot torcreting are created. Refractory materials are turned out on an industrial scale in OAO Kombinat Magnezit. They are used for the most worn parts of linings such as the tuyere zone in horizontal converters, the slag belt of ore-roasting furnaces (ORF), in the reaction zone of a Waelz kiln, ORF outlet assemblies, Kivcet unit arches, and Vanyukov furnaces. Lining life is increased by a factor of 1.5 – 2.5.

Combined Highly Resistant Lining of Furnace Chamber for Drying Nutritional Yeast Suspension

Service conditions for the lining of SRTs12.5/1500 NK furnace chamber in the Mozyr’ Nutritional Yeast Plant (MZKI), the nature of its breakdown, and combustion processes are studied. A refractory adhesive is developed and tested as a brickwork mortar. Use for impregnation of a furnace refractory lining of an aluminium-chromium phosphate binder of optimum density makes it possible to reduce refractory porosity and thereby increase strength by 30%, and thermal shock resistance by a factor of three. Alining of highly resistant mullite-corundum refractory based on fuzed materials is tested: a “chequerboard” furnace brickwork scheme is accomplished; a protective highly-resistant coating is used for repairing local breakage. As a result of introducing these measures combustion chamber lining life is increased by a factor of 2.5 – 3.0, i.e., from 2 – 3 to 9 – 10 months.