Periclase-chromite Refractories Research Articles

The mechanism of destruction of periclase-chromite refractories under the influence of acidic slag

Periclase-chromite refractories after operation under conditions of exposure to acidic slags are investigated. The microstructure and corrosion mechanism of refractories in fayalite melts are shown. Ways to increase the resistance of refractories are proposed.

Mechanism of Periclase-Chromite Refractory Breakdown Under Acid Slag Action

Periclase-chromite refractories are studied after operation under action of acid slags. The refractory microstructure and corrosion mechanism in fayalite melts are demonstrated. Ways of improving refractory stability are proposed.

Periclase-Chromite Refractory Decomposition by a Coal – Gas Medium During Copper Sulfide Raw Material Processing

The composition and structure of periclase-chromite refractories contacting the coal–gas atmosphere of copper-sulfide-ore smelting furnaces were studied. Combined effects of high-temperature suspensions of enriched copper concentrate and SO2 altered the chemical composition of the refractory surface and inner layers. The impurity contents (wt%) reached Fe 54.0, Cu 7.2, Zn 6.4, and S 1.8. Saturation of the surface layer with iron and nonferrous-metal oxides decreased its porosity and promoted the formation of low-melting compounds and eutectics. The periclase-chromite refractories were decomposed by exfoliation of layers with filled pores during alternating heat—cool cycles because of the different linear thermal expansion coefficients of the phases. The surface layer of spent refractories should be mechanically removed for recycling. The remaining part is suitable for producing refractory powders for various purposes.

The periclase-chromite refractory decomposition by the action of the pulverized coal and gas medium in course of copper-sulfide raw materials processing

The investigating results are given for the periclase-chromite refractories' composition and structure which are in contact with the pulverized coal and gas medium in the coppersulfide smelting furnaces. The high-temperature burnt copper concentrate and the sulfur dioxide gas suspensions combined action changes the surface and deep refractories layers chemical composition, with that the impurities content reach the value in weight percent: Fe 54,0, Cu 7,2, Zn 6,4, S 1,8. The refractory's surface layer saturation with the iron and non-ferrous metals oxides decreases the porosity and gives rise to low-melting compositions and eutectics. The refractory decomposition is induced by the shelling of the refractory surface layers with the filled porous taking place in course of the heating-cooling cycling because of the phase's thermal linear expansion coefficients. When the spent refractory disposal, it is feasible to separate mechanically the surface layer for the non-ferrous metals extracting, the rest part can be used for obtaining the refractory powder of various purpose.

Structure of Periclase-Chromite Refractories After the Service Life in Furnaces for the Processing of Sulfide Raw Material

The chemical and mineral compositions of periclase-chromite refractories used in the lining of the furnace for the processing of sulfide raw materials were investigated before and after the overhaul period. It was shown that dusty gas has an effect on the refractories composition and structure, causing saturation of the surface layer with both dust and gas components. Copper, zinc and lead penetrate the materials at a depth of up to 5 mm, whereas traces of elevated levels of sulfur associated with the formation of sulfates Fe12S11O51, MgSO4 and PbSO4 were detected at 20 mm deep. Waste refractories can be used as lining at the non-critical components of thermal units and kilns, and as refractory powder to prepare gun mixtures.

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.

Operating and Corrosion Features of Periclase-Chromite Refractories During Electrothermal Treatment of Lead-Containing Products

Features of an electrothermal unit periclase-chromite lining operation during treatment of lead- and zinc-containing products are studied. It is established that during operation a refractory lining is subjected to erosive and corrosive wear. The nature and degree of refractory breakdown depends on its location within elements of an electrothermal unit. Greatest wear occurs for a refractory lining in a smelting furnace roof and slag belt.

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.

Study of mineral and phase compositions of a furnace lining after melting crude ferronickel

Combined methods are used to study the lining of a ferroalloy furnace after service. It is established that periclase-chromite refractories are subject to chemical corrosion. Readily melting silicates and a metal phase form in a furnace lining, and reducing processes occur with participation of silicon, chromium and nickel sub-oxides.

Features of chromite ores from different deposits and their effect on the microstructure and properties of periclase-chromite refractories

With the aim of selecting possibilities for use in industry of chromite ores from different deposits in order to produce periclase-chromite refractories these ores are studied by optical and electron microscopy, and also chemical and differential thermal analysis: Indian, Iranian, South African and Turkish. High temperature changes that occur within them are described. Microstructural features for periclase-chromite refractories based on these chromite ores and the interconnection of indices are revealed that make it possible to recommend an ore for a specific application.

The effect of degassing technology parameters and the quality of periclase-chromite refractories on their wear resistance in vacuum chamber lining

The results of an integrated study of external factors on wear resistance of periclase-chromite refractories in vacuum chamber lining are discussed. It is established that the mineral composition and structure of magnesian-spinellide refractories are the least liable to transformations.

Ladle service under the conditions of vacuum-oxygen decarburization

The Izhstal plant has created a technology for treating corrosion-resistant steel by the method of VOD in a 30-ton ladle. The lining of the ladle is made of periclase-chromite refractories produced by the Magnezit Works JSC. The effect of the process parameters and lining patterns on the endurance of the ladle was studied in development of the process. The main factors determining the wear of the functional layer of the lining are the density of its joints, the composition of the slag of the refining period, the intensity of the mixing, and the thermal regime of the ladle between the heats. The pattern of the lining has been improved by reinforcing the slag line. The mixing regimes and the composition of the killing mixture have been improved where the consumption of lime and the proportion of aluminum to silicon are concerned. These measures have increased the endurance of the ladles by a factor of 2.2 and that of the refractory roofs by a factor of 2.5.

Experience in using periclase-chromite refractories in roofs of tilting open-hearth furnaces

The workers of the Azovsta’ integrated iron-and-steel works have determined the causes of early wear of main roofs of open-hearth furnaces. They have resorted to lining the main roofs by periclase-chromite refractories of grade LIIIV produced in Slovakia. The use of refractories of grade LIIIV has increased the endurance of the main roofs of open-hearth furnaces by 100 heats. A petrographic study has shown that the high operating properties of articles made of LIIIV are due to their composition and structure, obtained as a result of the use of high-quality initial materials (chromite ore and magnesite powder) and a modern manufacturing process. Introduction of the developed manufacturing process has increased substantially the endurance of the linings and reduced the number of cold repairs of the open-hearth furnaces and the consumption of refractories.

Magnesia refractories from Slovakian periclase

The Nikitovsk Dolomite Plant has produced an experimental industrial batch of magnesia articles based on Slovakian periclase. Results have shown that the articles made of Slovakian periclase correspond to the requirements of GOST 10888-76 for periclase-chromite refractories and GOST 4689-74 for periclase refractories.

Periclase-spinel refractories for rotary cement kilns

Results of an investigation aimed at the development of periclase-spinel refractories of the “second generation” are described. It is established that brucites can be a basis for the production of high-quality artificial spinel and periclase. The periclase-spinel refractory with these components has higher physical and ceramic properties than the periclase-chromite refractories used today in Russia for linings of rotary kilns.

Development of usage rates of pericilase — Chromite refractories for open-hearth and twin-bath furnace roof repairs

Based on the data of a detailed investigation with the use of multi-factor correlation and regression analyses, a complex of multi-factor models has been studied and constructed for the development of absolute usage rates of periclase-chromite refractories in ongoing repairs of the lining of the main roof and port roofs of open-hearth and twin-bath furnaces with capacities ranging from 200 to 900 tons. Calculations by the models demonstrated a sufficiently high accuracy of prediction.

Deformation and strength characteristics of magnesia-spinnellide refractories at elevated temperatures

We studied the thermomechanical properties of the heat resistant chromite-periclase refractories and three types of periclase-chromite refractories. It was established that the superior deformation and high-temperature strength characteristics of the chromite-periclase products ensure a more complete stress relaxation in the products during their service and reduce the wear of the linings of the melting furnaces.

Effects of melting parameters on the roof stability in a high-load electric steel-melting furnace

The central part of the roof in a large arc steel-melting furnace is made of periclase-chromite refractories and wears 2–3 times more rapidly than the edge. The wear rate is governed by spalling in the working surface.

Magnesia refractories from Korean periclase with magnesium sulfate bond

Investigations showed that by using Korean periclase powders, and magnesium sulfate as the bond, it is possible to obtain periclase, periclase-chromite and chromite-periclase refractories whose properties meet the requirements of the existing standards of the USSR. The main parameters of the technology for making such articles were worked out.

Periclase-chromite refractories based on fused clinker and sintered chromite concentrate

Periclase-chromite refractories based on fused clinker and sintered chromite concentrate