Results are presented for a laboratory study of the substance composition of a periclase-carbon torcrete mix for restoring a converter lining, comparative methods for testing a torcrete mix under laboratory conditions, and the main production parameters for a torcrete mix under existing production conditions. Industrial tests are performed in the converter section of the OAO MMK oxygen-converter workshop. The life of a torcrete layer is two melts.Semidry torcreting relates to a number of efficient technologies for servicing the lining of a steel-pouring unit during operation. In the oxygen-converter workshop (OCW) of OAO MMK for hot repair of the most worn zones of a converter lining, i.e. the pouring and tilting cradles, trunion zones, torcrete mixes of periclase-carbon composition are used. Since OAO MMK has a natural raw material base for producing refractories of basic composition, specialists of the technical services studies the possibility of preparing torcrete mixes for restoring a converter lining under actual production conditions, i.e., in the workshop of magnesia-dolomite refractories (MDRC) of OOO Ogneupor.In developing torcrete mix compositions under laboratory conditions the refractory filler used was periclase powder or composite material, consisting of fuzed periclase grains, bonded with flaky graphite by a synthetic resin. In order to improve the production and operating properties a combined binder was added to the composition of the torcrete mix, consisting of sodium polyphosphate and carbon-containing components (coal tar high-temperature pitch, SFP phenolic resin binder, Carbores), and special additions (silicate materials, bentonite, magnesium sulphate). Alongside the choice of these binder materials and additions the grain size composition of the torcrete mix was refined.In the first research stage a study was made of the adhesion properties of the compositions developed for degree of mix sticking with the refractory surface. Tests were carried out on plates with a cross section of 100´100 mm 2 , cut from periclase-carbon refractory. Plates were held at 1200°C in a laboratory furnace for 1 h, and then the torcrete mix moistened with water was applied to them. After settling, a visual estimate was made of the degree of adhesion of torcrete layer with the plate surface. For comparison a control mix adopted was series produced composition torcrete mix PUTMK-3 produced by NPO VOSTIO-Ural used in the OCW.From the results of the first stage of studying 22 developed compositions ten were selected exhibiting a high degree of adhesion with the refractory. Compositions with weak adhesive properties were excluded from further study. It should be noted that all of the composition selected contain sodium polyphosphate. In the first stage of laboratory studies a comparative estimate was made of the quality indices of laboratory specimens manufactured from torcrete mixes of control and test compositions in a laboratory hydraulic press under a pressure of 40 MPa. After pressing specimens were heat treated...
A technology for fabrication of refractory briquettes from spent periclase and periclase-carbon materials salvaged from decommissioned steel ladles has been developed. The briquettes can be used as a patching material to repair the worn refractory lining in oxygen converters. Tests of the patching briquettes were conducted at the MISW JSC with satisfactory results.Thermal power units in service in metallurgy and other sectors of industry require continuous control over the operating and maintenance conditions of the refractory lining. For the oxygen converter, the most effective methods for recovery of the lining are patching and protecting slag coating (scull) applied by means of a slag splashing technique. For preparation of the refractory material for patching and repair, production wastes -broken ceramics, rejected products, and spent refractory bricks -are typically used.At the MISW JSC, the waste lining materials, in particular periclase and periclase-carbon refractories, dismantled from decommissioned steel ladles and other heat engineering units have been directed in large quantities to a dump site for outdoor storage. It was deemed expedient to use these wastes as the precursor material for fabricating refractory briquettes for patching the converter lining. Initially, laboratory tests were carried out. Therefore the precursor materials tested were periclase and periclase-carbon powders prepared from spent refractory components. The physicochemical properties of the powders are given in Table 1. The bonds tested were powdered commercial lignosulfonates (CLS) and a powdered phenol-based binder (PB). Water was added to the mix components to a moisture content of 2.0 -2.5%.The test specimens were molded using a PG-100 hydraulic laboratory press under a pressure of 60 MPa; the green preforms were dried in a laboratory drying cabinet at 150°C for 8 h and then at 160°C for 17 h in the drying tunnel oven No.
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