Refractory Lining for Alumina Electrolytic Cells

This paper provides the specifications of a refractory lining for alumina electrolytic cells capable of ensuring good resistance to corrosion by the cell chemicals, while maintaining desirable thermal characteristics during service.
Several refractory materials were tested in the Alcan's standard electrolysis bath test. Also, using Alcan's standard procedures, different insulating refractory products were tested for their gain in thermal conductivity after compression.     

Unmolded barrier materials based on mechanically activated mixtures for lining electrolyzers

Research results are reported on the use of mixtures consisting of mechanically activated fractions in place of traditional lining materials, which are used in making aluminum by means of dry barrier mixtures with various ratios. There is shown to be a positive effect from the mechanical activation of these unmolded barrier materials on the quality of the electrolyzer lining. __________ Translated from Novye Ogneupory, No. 2, pp. 61–64, February, 2008.     

Study of the interconnection of aluminum electrolyzer life with corrosion of its casing

It is confirmed that an aluminum electrolyzer casing is subject to electrochemical corrosion. It is established that on reaction of electrolyzer associated gaseous products with the electrolyzer casing there is formation of fluorides of bi- and trivalent iron, and also iron fluorides of non-stoichiometric composition. It is shown that the fluoride layer formed does not protect the casing surface from further corrosion. In order to protect the electrolyzer casing it is necessary to fasten a refractory barrier layer. More reliable heat insulation should be used in order to maintain the optimum casing heating temperature. Translated from Novye Ogneupory, No. 1, pp. 39 – 42, January 2009.     

Contemporary aluminum electrolyzer refractory materials

The problem of refractory materials for lining the cathode casing of contemporary electrolyzers with a power of 300–500 kA, closely connected with the service life of the electrolyzer bath, is discussed. For this purpose it is possible to use plates of the composition SiC-Si₃N₄, artificial build-ups of ramming mix, and also TiB₂ for more effective protection and operation of aluminum electrolyzers that are favorably reflected in the production regime and optimization of production. Translated from Novye Ogneupory, No. 9, pp. 13–15, September 2008.     

Dismantling the lining of an electrolyzer cathode unit for aluminum production using hydraulic press equipment and diamond cutting tools

Technology is considered for dismantling the lining of a aluminum electrolyzer cathode unit for major overhaul directly within the electrolyzer building. In order to accelerate breakdown of the lining and reduce the effect of impact and vibration loads during dismantling on the neighbourhood during repair of the electrolyzer, cathode dismantling is performed using hydraulic press equipment for impact-free breaking of materials using diamond tools for cutting and boring. Acceleration of dismantling is achieved as a result of the use of hydraulic equipment making it possible to create within the electrolyzer cathode lining material local nonuniform pressure distribution providing crack formation breaking the integrity of the lining.     

Pneumatic separator for separating refractory raw materials sizes

Conclusions The use of the pneumatic classifiers described will intensify the separation of refractory materials into the finer grains, increase the efficiency of the classification relative to that achieved with centrifugal separators, and simultaneously improve the extraction yield without reducing the quality of the products.Using the proposed classifier it is possible to obtain several products of different size, which will make it possible to synthesize rational grain-size compositions in refractory bodies. The classifier can also be used for extracting dust from materials before their separation on vibrating screens, which will reduce the dust content of the workshops.Translated from Ogneupory, No. 6, pp.17–21, June, 1972.     

Brickwork of furnace lining of high-temperature metallurgical plants produced from special refractory materials

The feasibility of applying specially designed refractory articles is demonstrated. Through the use of such articles it is shown that it is possible to reduce the thermal stresses that are experienced in the use of lining, markedly reduce separation of refractory products, and reduce heat losses through the brickwork by virtue of the presence of a heat-insulating layer in a given article consisting of refractory material and artificial pores as well as gaps for placement of additional heat insulation. These types of refractory products may be compacted and either roasted or unroasted and may also be manufactured according to the technology used in the fabrication of concrete. A press mold has been produced and put into production at the refractory plant of OAO NTMK for the purpose of fabricating specialized articles. The articles have successfully undergone tests, introduced into the crown of open-hearth furnaces, and are used for lining of rotary furnaces. The life of the linings was increased 1.3 – 1.4-fold     

Study of the mineral and phase composition of aluminosilicate refractory ShPD<Subscript>M</Subscript>-45 after service in an aluminum electrolyzer of OAO Zaporozh’e aluminum combine

Comprehensive studies have established that ShPD_M-45 refractory produced by OAO Zaporozhogneupor exhibits good anticorrosion properties towards the action of electrolysis bath corrosive extraneous components. The degree of degradation of ShPD_M-45 refractory after two years of service is 10%. The average concentration of entry of Na_g and F_tot into ShPD_M-45 refractory through hearth blocks with 50% graphite is correspondingly 4.08 × 10^–4 and 3.32 × 10^–4 g-mole/day. It is established that ShPD_M-45 refractory is a more reliable barrier material than unmolded aluminosilicate mixes. The penetration rate of corrosive components of the electrolysis bath into unmolded aluminosilicate materials is greater by a factor of 10 – 30 than for ShPD_M-45 refractory. It is shown that the protective function of titanium-containing components and glass phase in an electrolyzer lining develops as a result of forming fluoride, subfluoride and oxyfluoride titanium compounds. Industrial approval of ShPD_M-45 refractory under OAO Zaporozhe Aluminum Combine conditions has shown that it exhibits good operating properties in electrolyzers with hearth blocks with 50% graphite The authors thank D. V. Pruttskov and D. Yu. Boguslavskii for help with this work. Translated from Novye Ogneupory, No. 3, pp. 45 – 50, March 2009.     

Experience with repairing shaft furnace lining

The Alineka Company has produced dry mixtures of the refractory concretes BRAB40I15** and BRAB50I17** as well as light thermally insulating components I-9 and I-11 for the current and restorative repair of the lining in a shaft furnace. The current and restorative repairs have been performed professionally by the Kudrii Company at 11 organizations, which has confirmed the reliability and improved working life of lining made of these materials (not less than two years). The lining reconstruction performed by Tekhnosakhar has eliminated existing deficiencies in the working technology (lumping) on the one hand while on the other it has reduced the consumption of fuel (energy saving) and raised the amount and competitiveness of the final product (lime), while increasing the throughput. Translated from Novye Ogneupory, No. 12, pp. 6–10, December, 2008.     

New Formulations of Fused Periclase-Based Refractory Materials for the Lining of Steel Ladles

New formulations of fused periclase-based carbon-containing refractory materials for differentiated use in the lining of steel ladles (bottom, slag zone, and walls) are proposed. The use of new refractory materials made it possible to improve the lining durability from 80 to 100 heats.     

Possibility of using fibrous thermal-insulation materials for lining electric furnaces containing a reducing atmosphere

Conclusions A study has been made of the possible use of fibrous thermal-insulation materials for the lining of furnaces operating with a reducing gas. The results of the study make it possible to recommend the use of ShVP-350 tiles at the maximum working temperature of 1200°C and products made from mullite-silica fiber and mineral wadding over the same interval of temperatures as in air, i.e., up to 1150 and 600°C, respectively. The use of fibers made from rocks with a high concentration of iron oxides is ruled out because of their low stability in a reducing atmosphere.The thermal conductivity of the fibrous materials in a reducing atmosphere is 25–40% higher than its value in an air atmosphere.The lowering of the thermal conductivity of fibrous linings in a reducing atmosphere makes it preferable to use them rather than normal linings of equal thickness because of their thermal-insulation properties. The use of the fibrous linings, moreover, helps to keep stable the specified composition of the furnace atmosphere. The time taken to restore this after the door has been opened is 1.5–2.0 times faster than that required for furnaces with the normal lining materials.Translated from Ogneupory, No. 2, pp. 8–11, February, 1984.     

Use of mineral coal ashes in insulating refractory brick

Coal ash from Candiota thermoelectric power plant in southern Brazil is a waste generated in great amount. Current estimates indicate that coal ash production is likely to reach 2.000.000 tons per year. Of this total, only 10% are commercialized, so the price of this material is very low. In this work, it was investigated the use of coal ashes in a composition of refractory insulating brick. In coal combustion process, fly ashes and bottom ashes are generated. Bottom ashes are formed by partially fused ashes that precipitate to the bottom of the boiler, due to their coarser particle size. Therefore, it was analyzed fly ash addition in a refractory body and the addition of bottom ashes, partially replacing chamote (calcinated clay). The results showed that the effect of the ash is small in the fired materials. In terms of technological characterization, the bricks formulates with coal ash were considered suitable to commercial brick standards. Density and thermal conductivity of the refractory bricks with coal ashes had revealed to be similar the commercial products. Then, the use of ash is economical attractive and technical feasible. Translated from Novye Ogneupory, No. 6, pp. 60–63, June 2008.     

Design of Composite Ladle Shroud for Improving Thermal Shock Resistance

A ladle shroud is one of the functional refractories for continuous casting,which undergoes severe thermal shock by molten steel when used without pre-heating.The composite ladle shroud with an insulating liner presents excellent thermal shock resistance.Finite element simulation is an effective method to explore the maximum thermal stress for predicting the thermal shock resistance of ladle shrouds.In this paper,the influence of the lining materials and the structure of ladle shrouds on the thermal stress distribution is systematically researched.The working mechanism of the lining material on the body material is also presented.Lining materials with low thermal expansion,elastic modulus and thermal conductivity are helpful to improve the thermal shock resistance and an optimum lining thickness is suggested.The lining material can both serve as thermal resistance for the body material to buffer the thermal stress,and apply a strain load to the body material by the thermal strain to increase the stress.     

Properties of refractory materials for primary aluminum production electrolyzers

Results are provided for a study of changes in the properties of barrier materials during laboratory and industrial tests. Some autopsy results are presented for electrolyzers with a different service life. Directions are indicated for improving barrier layer properties in electrolyzers due to the use of new technology and equipment intended for vibration compaction of materials directly in electrolyzer socles. __________ Translated from Novye Ogneupory, No. 3, pp. 96–102, March 2008.     

Improving thermal insulation for graphitization furnaces

Alternative materials are proposed for the lateral thermal insulation in graphitization furnaces. It is possible to reduce the loss of heat and the consumption of electricity by using carbon dust for insulation, and it is also possible to use plates of thermally and electrically insulating carbon material to hold it in the furnace. Translated from Novye Ogneupory, No. 12, pp. 3–5, December, 2008.     

Practice of application of refractory concrete in industrial furnaces

The Teploograzhdenie Research-and-Production Company has developed refractory concretes with service temperature of 1150–1650°C which have been successfully used as car bottom lining in tunnel furnaces, block lining of the hearth and lower parts of thermal furnace walls (together with the Termostal’ JSC), lining of roof panels of a continuous furnace, and burner stones. __________ Translated from Novye Ogneupory, No. 11, pp. 18–19, November, 2006.     

A method for repairing tunnel furnace cars

The NPF Alineka company has developed refractory construction concretes BRSB20I11 based on water glass and concretes BRAB50I13 and BRAB50I15 with the traditional content of aluminate cement, which have a high class of thermal resistance (T₁40–T₁80) and the maximum application temperature of 1100–1500°C, as well as heat-insulating lightweight plates of size 300 × 200 × 80 mm and density 400 kg/m³, with a maximum application temperature of 1150°C. These materials can be used as lining of tunnel furnace cars for firing wall ceramics, as well as porcelain and faience products. The experience in repairing a furnace car is described. __________ Translated from Novye Ogneupory, No. 5, pp. 15–19, May, 2007.     

Rotary kiln corrosion-erosion-resistant linings

The properties of magnesia refractories are studied with the aim of determining the possibility of their use for lining rotary kilns. Periclase-chromite refractory PKhPP has been developed with an increased Cr₂O₃ content, whose use combined with a laying cement, operating by the principle of self-propagating high-temperature synthesis, in a developed “slotted” single-layer lay-up of the furnace reaction zone, made it possible to increase the lining life of industrial rotary kilns by a factor of 1.5–1.8. __________ Translated from Novye Ogneupory, No. 4, pp. 13–17, April 2008     

The performance of the refractories in the stack of a 2700-m3 blast furnace

Conclusions The refractory lining of the cooled part of the stack eroded before the end of the campaign and the blast furnace was operated for 18 months without this masonry.In the furnace the refractory impregnated with the dustlike and gaseous products of the melting materials, viz., the ferrous compounds of the ore in the charge, oxide vapors of the alkali metals, and the components of the slag melt. The chemical conversions in the refractory result in the erosion of the lining of the stack. The refractory lining of the noncooled part of the stack remains in a satisfactory condition and may serve for 10 years or more without major patching.Hydrogen and soot carbon are not primary causes of the failure of the stack lining, but it would be difficult at this stage to give an unequivocal answer to the question of their contribution to the process of erosion.It was established that sphalerite deposits are confined to the heat cracks in the refractory and the joints in the masonry of the refractory lining of the shaft.Translated from Ogneupory, No. 4, pp. 18–26, April, 1977.     

不烧漂珠隔热耐火制品的研制

以高铝水泥和漂珠为主要原料．研制出一种新型不烧漂珠隔热耐火制品。该制品生产工艺简单，节能，成本低．特别适宜制作异型制品。