Highly refractory unfired products with a magnesium-phosphate bond

Conclusions In laboratory conditions compositions were tested for making (by the semi-dry method) refractory articles based on fused magnesite with a bond made from magnesium monosubstituted phosphate.These unfired articles have high strength and spalling resistance.The properties of the developed unfired bodies made from fused magnesia can be recommended primarily for making highly refractory ramming linings and articles (including heat-resistant tubes) for high-temperature furnaces of the laboratory type.     

Production of unfired tarred -dolomite brick and its service in 100-TON oxygen converters

Conclusions The use, in the production of unfired articles, of highly sintered granular dolomite without additional grinding and coal-tar pitch with a high content of pitch, ensures, after pressing of the hot bodies, the production of dense and strong articles capable of being stored in air in winter for 10–12 days.To further improve the resistance of the unfired lining, it is necessary to continue the investigation of the effect of metallurgical factors on the resistance of the unfired refractories during service in converters, and to establish the optimum parameters for the oxygen-converter melting cycle.Translated from Ogneupory, No. 2, pp. 15–19, February, 1966.     

A g.l.c. simulated distillation technique to study changes in the composition of coke-oven road tars in service

A simulated distillation technique has been developed making use of gas-liquid chromatography (g.l.c.) for the quantification of oils present in road tars derived from coke-oven crude tars. The tar-oil constituents are grouped into boiling temperature ranges which coincide with those of fractions or cuts used in a standard (conventional) distillation test. The g.l.c. method caters for the wide range in boiling temperatures of tar-oil constituents and for the fact that only about half of the tar substance injected is eluted from the column. In the analyses of tars recovered from road surfaces a means has been found to compensate for the presence of detritus in the tar. This method has several important advantages over the standard distillation procedure. Its accuracy and precision are superior and it can be used to determine constituents boiling as high as 400°C (673 K). (Due to the thermal sensitivity of coal tar hydrocarbons, the temperature in the standard distillation test may not exceed 340°C.) The g.l.c. method is more rapid and the small amount of tar required facilitates the analyses of tars weathered in road surfaces. In addition, repeat analyses can be carried out without inconvenience and the handling of the tar material is reduced. The g.l.c. method provides a powerful research tool for the study of the weathering of road tars. This paper gives the results of some weathering investigations. These show that even constituents with high boiling points (in the range 370–400°C) may be partially lost from tars in the first year of service. Oil losses are most rapid in the first year, but all constituents with boiling points below 300°C may be lost after prolonged service. From data provided by this method and measurements of the change in viscosity of tars on weathering, it has been possible to conclude that, in the case of coke-oven tars, evaporation is the major weathering mechanism in the South African Highveld climate. There is a good correlation between oil losses and the hardening of tars, particularly in the early life of a spray-and-chip surfacing. Such studies have led to the development of improved road tar binders with economic benefit to the South African road industry.     

Reinforcing unfired magnesia bodies and firing them without preliminary drying

Conclusions A technology has been developed in industrial conditions for strengthening unfired (green) magnesia ware based on additions to the batch of a solution of sulfite liquor. The use of this technology made it possible to set the ware from the press directly on the kiln cars.The important feature of the developed technology is the possibility of firing the ware without preliminary drying and without changing the firing schedule and output of tunnel kilns.Test ware fired in a tunnel kiln without preliminary drying, in external appearance and properties were no different from those made by the usual method.The developed technology for reinforcing the green ware made from basic bodies is recommended for use in existing plants, those being built and those being projected.Setting of freshly pressed brick of magnesia bodies directly from the press onto kiln cars is specified in the projects for new factories.     

Upgrading of flash pyrolysis tars to synthetic crude oil: 1. First stage hydrotreatment using a disposable catalyst

The hydrotreatment of tars produced by flash pyrolysis of Millmerran (subbituminous), Loy Yang and Yallourn (both brown) Australian coals was investigated in a continuous reactor containing a packed bed of sulphided steelwool. Reactor performance and product yields are reported for each tar. Overall mass balances of 96.7–100.3% and carbon balances of 96.0–100.2% were achieved. Recovered yields of product oil were 82.7–86.8%, 62.1% and 75.5% wt/wt dry, char-free tar for Millmerran, Loy Yang and Yallourn tars respectively. The steelwool reactor was found to decrease the coking propensity, specific gravity, viscosity and heteroatom levels and to increase the hydrogen content of the tars. It also acted as a filter to remove the char fines present in the tar. The operating life of the reactor was limited by the build up of carbonaceous deposits within the steelwool.     

Weathering of road tar. I

Crude tars from six sources have been used in a full-scale experiment to determine the physical and chemical changes that occur in road tar used in wearing-course macadam. Samples taken from the road at intervals up to two years have been studied in the laboratory. It has been shown that when tars weather, there is an increase in viscosity due to two main processes, evaporation and oxidation. In the oxidation mechanism, ‘C₂ resin’, soluble in pyridine but not in benzene, is formed from material of lower molecular weight; it increases both the viscosity and the temperature coefficient of viscosity, so that in cold weather very high viscosities are attained. In the case of lower-gravity tars, evaporation and oxidation account for similar amounts of hardening, but with coke-oven tars, evaporation predominates.     

Vibratory compaction of tarred dolomite bodies

Conclusions The vibratory compaction method using heated tarred dolomite bodies yields unfired articles with a high hydration resistance.The high density structure of vibrated products was obtained with a frequency vibration of 6900 osc/min.It is desirable to use bodies with a continuous grain-size composition to get better vibrocompaction of the articles.Translated from Ogneupory, No. 6, pp. 10–14, June, 1967.     

Evaluation of low-temperature coal tars by a rapid,detailed assay based on chromatography

A rapid, detailed assay, based largely on both liquid and gas chromatography, was developed for low-temperature coal tars. With the use of this assay, the pounds per ton of coal of various compounds of commercial interest could be determined, thus supplying the information needed for an economic evaluation of the tars and the carbonisation processes. The amounts of about 100 individual compounds of several classes were involved, including light oil components, tar acids and bases, and neutral-oil components such as naphthalenes and straight-chain paraffins and olefins, and the total amounts of these classes in the entire tar. The results for six different tars from the same coal were chosen as examples.     

Unfired refractories bonded with coal tar pitch

Conclusions Medium-temperature coal tar pitches are effective bonds for making unfired dolomite and dolomite —magnesite refractories by pressing bodies heated to 100–120°C. The features of the refractories with a pitch bond are the higher contents of carbon resistant to oxidation (about 4%), and the higher compressive strength (400–500 kg/cm²), and finally the higher hydration resistance (10 days).Refractories bonded with pitch are much better than products containing tar, and accordingly offer a greater resistance when used in oxygen converter linings.Translated from Ogneupory, No. 3, pp. 6–15, March, 1971.     

Unfired dolomite refractories with increased hydration resistance

Conclusions The use of dolomite burnt in grain form for the manufacture of unfired goods with a tar bond makes it possible to obtain refractories with a high hydration resistance and with high physicomechanicai properties. Coal tar with a 65–70% pitch content should be used as a bonding agent.Sintered grain dolomite should be added to the batch without being ground, preferably in combination with finely ground metallurgical magnesite or magnesite-dolomite clinker.     

Viscosity modification of flash pyrolysis tars

A study was made of the effect of a number of additives on the viscosity of a characteristic tar produced by the flash pyrolysis of indigenous Australian coals. The results indicate that aliphatic compounds are more effective than aromatic compounds in lowering the viscosity. This observation is of significance in the selection of suitable recycle solvents and the dissolution of aged tars.     

Coke quality on adding coking byproducts to the batch

Conditions for the granulation and heat treatment of coking byproducts—heavy coal tar, acid tars, and distillation residues—are developed so as to produce suitable additives for coking batch. It proves possible to improve poorly clinkering batch by adding a mixture of coal and acidic tar from the sulfate department.     

Manufacture and testing of tar-bonded dolomite-magnesite brick

Conclusion The use of calcined dolomite powder without supplementary grinding, preprocessed with fused coal-tar pitch, for making unfired goods with a tar bond makes it possible to produce refractories with a high resistance to hydration and with other satisfactory properties.The testing of dolomite-magnesite brick with a tar bond in the lining of a ladle, imitating a converter with oxygen blow, showed that it had a high wear resistance; the wear intensity is no different from that of periclasespinel brick.Tarred dolomite-magnesite goods with metal cladding showing certain advantages in service over unclad products, need to be tested in large quantities, especially in the charging side and in the throat of the lining of the converter.To obtain data more reliably reflecting the life of dolomite-magnesite brick with a tar bond in converters working with oxygen, the authors should carry out repeat tests of these refractories in conditions excluding the long intermelting downtime-Editors.     

甲烷及水蒸气对生物质催化气化合成气和焦油的影响

以松木木屑为生物质原料，在两段式反应器上进行甲烷、水蒸气对生物质催化气化影响的实验研究，考察了甲烷与生物质之比α、水碳比S/C对气体产率、碳转化率、焦油产率、焦油组分和露点温度影响的变化规律。结果表明：α从0增加到0.4，合成气中H₂的产率增加了57.4%，甲烷的加入有利于生成富含氢气的合成气；α为0.2时碳转化率最高，为86.9%，焦油产率下降了30.5%，第二、五类焦油的产率达到最低，可见适量CH₄的添加能促进焦油的转化，特别是大分子焦油和酚类的反应。随着S/C的提高，H₂产率升高，CO产率降低；S/C从1增加到1.5，各类焦油的含量均有所降低，当S/C进一步增加到2时，第二、五类焦油含量却有所上升，说明水蒸气可以促进焦油向气体分子转化的反应，但过量的水蒸气抑制酚类和大分子焦油的分解。总之，甲烷和水蒸气的适量添加均可以提高合成气中H₂的含量，降低焦油产率，提高合成气的品质，有利于气化产物的进一步利用。     

Manipulation of the ash flow temperature and viscosity of a carbonaceous Sasol waste stream

In 2001 Sasol investigated the possibility to convert a Sasol-Lurgi MK III fixed bed dry bottom coal gasifier at the former Sasolburg coal-to-liquids plant to a slagging gasification process and selected the Lurgi Multi Purpose Gasification (MPG) process for this purpose. At the time the MPG process was considered as a possible technology option suitable for the gasification of feedstocks which are difficult to manage, for example solid-liquid mixtures which are unsuitable for conventional solids or liquids processes and furthermore tars with a large variety of properties and high solids content have been gasified successfully.The most obvious differences between the feedstocks previously gasified, compared to the Sasol dusty tar, were found to be the viscosity and melting point of the dusty tar. The viscosity of the Sasol dusty tar mixture (as received) was higher than a factor of 10 of the previously used feedstocks. Another important feedstock property is the ash melting point of the feed within the gasifier. Ash particles fed with the tar melt in the high temperature zone of the flame. Molten ash particles, which hit the gasifier wall, will solidify and stick to the wall, if the wall temperature is below the melting point of the ash. The melting point of the dusty tar ash is 1380 °C and a fluxing agent has to be added to the dusty in order to reduce the melting temperature below 1250 °C to limit excessive wear of the refractory lining.Two approaches were evaluated in order to lower the viscosity, i.e. milling of the dusty tar and addition of low viscosity feedstocks to the dusty tar. It was concluded from this study that the viscosity of dusty tar can be decreased with the addition of specific waste solvent streams. The ash fusion temperatures of dusty tar can be lowered with the addition of a fluxing agent. The addition of spent Fe-catalyst as fluxing agent was also investigated, but was found to be not as effective as limestone. In some cases the addition of Fe can cause the acid/base ratio to change in such a way that the ash fusion temperature increases.In conclusion it can be highlighted that the ash flow temperature and viscosity of the Sasol dusty tar stream, and possibly other carbonaceous sources as well, can be decreased to acceptable values for slagging gasification applications. The results clearly show in both oxidizing and reducing atmospheres the Fe-catalyst was transformed into the slag melt as either Fe₂O₃ under oxidizing conditions and FeO under reducing conditions. The slag showed no sign of metallic Fe and was very homogeneous under oxidizing and reducing conditions. Spent Fe-catalyst can be discarded in a safe and environmentally acceptable way during high temperature gasification.     

Phoretic phenomena in tar vapor-particulate mixture separation from fuel gas streams

Analytical models were developed to predict the performance of a spray scrubber for separation of tars from gasifier off-gas streams. The models included heat transfer, mass transfer, condensation, nucleation, temperature and flow fields, and various phoretic phenomena involved in droplet-particle and droplet-vapor interaction and collection. The models indicate that for the tar particulates, both Brownian diffusion and inertial impaction, rather than diffusiophoresis and thermophoresis, are the more important phoretic forces causing the collection. For the limiting case of all tars being present only as vapor, the efficiency of their removal by condensation on water spray droplets could be extremely high. Scrubbing experiments were carried out on the hot gas/tar stream evolved from the simulated devolatilization section of a laboratory fixed bed gasifier. The combined overall collection efficiency for a mixed particulates and vapor stream compares satisfactorily with the model predictions.     

Effect of the fineness of alumina and certain additives on the properties of alumina slips and products

Conclusions Slip made from ground alumina from the Podol'sk Factory possesses a high sedimentation stability, a low casting-up rate, and a high density and strength.Incorporating additions of GKZh-10 to accelerate the vibrogrinding of the alumina in preparing high-quality ceramics, needing to have high strength and dielectric properties, is undesirable. Introducing it during the ball-mill grinding for producing corundum ceramics which need not have specially outstanding properties is quite justified.The optimum quantity of magnesia in the slip from the point of view of its rheological properties is 0.07–0.2%.An addition of unfired technical alumina can be advantageously made, together with the MgO modifier, which permits a substantial reduction in the closed porosity and an increase in the apparent density of the articles.Translated from Ogneupory, No. 7, pp. 39–45, July, 1971.     

Effect of Fused MgO-ZrO_2 Clinker Addition on Thermal Shock Resistance of MgO-ZrO_2 Unfired Bricks

MgO-ZrO2 unfired bricks with ZrO2 content up to 8% at the interval of 2% were prepared,using fused magnesia(MgO:97%)and fused MgO-ZrO2 clinker(ZrO2:14.33%)as starting materials and phenolic resin as binder.The effects of ZrO2 content on thermal shock resistance(TSR)and other properties such as cold and hot modulus of rupture have been investigated.Residual cold modulus of rupture ratio after heating at 1 000 ℃ and quenching by air blowing was adopted to characterize TSR.Addition of the MgO-ZrO2 clinker impr...     

An investigation of the use of size exclusion chromatography for the determination of molar mass distributions and fractionation of coal tars

The use of size exclusion chromatography (SEC) for the determination of molar mass distribution and fractionation of coal tars has been investigated. The construction of a calibration graph based on typical components of the tars for use in the determination of molar mass distributions has revealed anomalously low retention volumes for phenols and amines when THF is used as the mobile phase. Consequently the molar mass distribution for a tar with a high phenolic content was not reliable when determined in THF but chloroform was shown to be a suitable solvent for this purpose. However the effect was used to fractionate the tar into two components, one of which contained a mixture of mainly phenols and long chain paraffins while the other was composed predominantly of polynuclear aromatics. A coke oven tar of low phenolic content was also fractionated into two components according to molecular weight and the fractions characterised in detail.     

Obtaining alumina insulating refractories with polystyrene additions

Conclusions A technology was developed and tested for making alumina insulating refractories by the combustibleadditives method with an apparent density of about 1 g/cm³ with outstanding properties.The use as combustible additive of foamed polystyrene in the form of fine fractions enabled us to obtain articles having a uniformly distributed fine spherical pore system and low thermal conductivity.The vibromolding method enabled us to use molding bodies with a relatively low moisture content, and to obtain articles with uniform density.We confirmed the possibilities of using unfired commercial alumina in the production of alumina insulating products, and clarified the advantages of incorporating titanium dioxide (up to 1%) as a mineralizer, which reduces the sintering temperature.Translated from Ogneupory, No. 3, pp. 15–20, March, 1972.