Search Results (22)

The recycling of used lead–acid batteries is currently the main source of lead in the world. More than 50% of the weight of a used lead–acid battery is battery paste, in which lead occurs in compounds with oxygen and sulfur. In pyrometallurgical processes of battery paste, coke or coke breeze is used as a traditional additive acting as a fuel/reducer. Due to the constantly high prices of these materials, research is being carried out to find alternative (equally efficient but cheaper) carbon-bearing materials. Those materials can be technological replacements for coke or coke breeze in pyrometallurgical processes. The aim of the presented work was to check the possibility of using fine-grained carbon-bearing materials, in the form of anthracite dust and coal flotation concentrate, for battery paste processing, as replacements for traditionally used coke and coke breeze. As part of the presented work, the following tests were carried out: thermogravimetric tests using battery paste, processes of smelting battery paste in a pit furnace, and processes of smelting battery paste in a rotary furnace. The research results indicate that fine-grained carbon-bearing materials, in the form of anthracite dust and coal flotation concentrate, can be successfully used as a replacement for traditionally used fuels/reducers. Full article

The combustion of briquettes made from organic and industrial residues in small boilers requires researchers to consider the characteristics of this type of fuel and methods of its combustion. For the efficient combustion of fuel briquettes, a layered combustion method with the ability to regulate the supply of combustion air is better suited. The purpose of this research is to study the thermal technical conditions of briquetted fuel combustion. In order to carry this out, a stand was created, which made it possible to determine the combustion efficiency of this type of fuel. Two types of briquettes were studied: one with 30% sunflower husks and 70% leaves, and one with and 70% sunflower husks and 30% coke breeze. The combustion results of the briquettes show that heat loss from chemical under-burning was no more than 6.25%. To determine the temperature distribution in the fuel layer, a model of unsteady heat transfer in a fixed layer was used. A calculation of the temperature fields in the layer of burned fuel briquettes was carried out, which showed that the most favorable conditions for burning briquettes were created with a layer about 15–20 cm thick for both burned briquette options. The temperature was in the range of 450–750 °C, which on the one hand corresponds to experimental data and on the other hand provides a combustion regime that occurs with a relatively low loss to the environment. This installation and mathematical model will help future studies based on the processes of other types of organic waste combustion with a grate system. Full article

This article summarises the possibility of replacing the coke breeze sintering fuel with an economically and ecologically more suitable fuel, anthracite. The main focus is on the possibility of replacing coke breeze with anthracite, during which, the replacement process is accelerated and the other properties are also affected. The analyses performed showed that the replacement of coke breeze with different amounts of anthracite does not have a negative effect if the initial permeability of the sintering bed is the same. Full article

In this study, the feasibility indicators of the injection of coke breeze for blast furnaces (BFs) were tested. Experiments were conducted on the combustion behavior of coke breeze at different particle sizes, and the effects of ratio of coke breeze in pulverized coal on the combustion performance of blends were studied. On the basis of the above experiments, industrial tests involving injecting coke breeze after milling were carried out in 3# BF of Shougang Jingtang. The results show that most of the coke breeze particle sizes were distributed above 1 mm. The grindability and combustion performance are poor, so the material needs to be ground before mixing with pulverized coal. The best combustibility can be obtained by using a particle size of less than 8.74 μm of coke breeze in the injection. With the increase in the coke breeze ratio, the combustion performance of blended coal worsened; the negative effects of coke breeze can be improved by increasing the proportion of bituminous coal. According to the results of industrial tests, 8% coke breeze in blends had no negative effect on the smelting state, and the output of the BF increased slightly. Industrial tests proved that coke breeze can partly replace anthracite for BF injecting, which reduced the cost of hot metal while realizing the high value-added resource utilization of coke breeze. Full article

The global steel industry uses fossil fuels to produce millions of tonnes of iron ore sinter each year. Sintering is an energy-intensive process that fuses iron ore and flux to produce material that balances a high mechanical strength at a sufficient particle size to ensure a macroporous burden in the blast furnace to enable rapid gas flow. As significant CO₂ greenhouse emissions are emitted, the defossilisation of these CO₂ emissions is vital to net-zero carbon targets. Two iterations of a new biomass–coal hybrid fuel (ecoke^®(A) and ecoke^®(B)) were compared with coke breeze and an anthracite coal using oxygen bomb calorimetry, simultaneous thermal analysis (STA) combining thermogravimetry and differential scanning calorimetry, and isoconversional kinetic modelling and pyrolysis–GCMS to study the volatile matter. The calorific values of both ecoke^®(A) and (B) were marginally higher than that of the coke breeze: 27.9 MJ/kg and 27.8 MJ/kg, respectively, compared with 26.5 MJ/kg for the coke breeze. A proximate analysis revealed both ecoke^® samples to have higher volatile matter contents (ca. 12–13%) than the coke breeze (7.4%), but less than the anthracite coal (ca. 14%). The thermogravimetric analysis of the burnout kinetics of the fuels heated up to 1000 °C, at heating rates from 5 to 25 °C/min, showed that that the coke breeze and anthracite coal had higher ignition and burnout temperatures than the ecoke^® samples. Kinetic analysis using the Freidman and Ozawa methods found that the ecoke^® samples showed comparable maximum mass loss rates to the coke breeze but lower activation energies. From these results, both ecoke^® samples have the potential to replace some of the coke breeze in the sintering process or EAF processes to help achieve net zero by offsetting up to 30% of the CO₂ emissions. Full article

This article presents the results of a study on metallurgical slag reduction using biomass such as Spent Coffee Grounds (SCGs). The proposed solution is a new aspect of searching for alternatives to standard reducers used in pyrometallurgical processes of metal production. Its gasification yields significant amounts of hydrocarbons, which are excellent reducing agents in such processes. The research results of copper slag reduction with the use of SCG biomass indicate this process is characterised by lower carbon dioxide emissions compared with the process using solid fuels such as coke and coke breeze. The addition of SCG as the reducer ensures the decrease in copper content in the slag to 0.32 wt.%, which corresponds to the increase of so-called relative decopperisation degree even up to 96.9%. As the decopperisation degree of slag increases, significantly more intense reduction in lead oxides during the reduction process is observed. The smallest lead content in waste slag of 0.91 wt.% was obtained for the slag reduction process with 7.56 wt.% of SCG as the reducer and the process duration of 1.5 h. Full article

In order to increase agglomeration production and improve its quality while reducing energy consumption, a new intelligent blending method has been established at Ansteel to optimize its sinter blends. The statistical model of the ore blending results shows that (1) a blending ratio of 47.2% Ore A and 52.8% Ore C corresponded to the best sinter yield of 72.44%. (2) From the viewpoint of sinter reducibility, sinter basicity should not be less than 1.98 when the proportion of Ore A in the blend is more than 35%. Due to the low mixing efficiency of disc pelletizers, Ansteel has therefore gone through a massive technical transformation at Sinter Plant 3 to replace its 16 existing disc pelletizers with one drum granulator. Since the installation of the drum granulator, the standard deviation has decreased from 1.517 to 0.7332 for total Fe (T.Fe) and from 0.146 to 0.0956 for basicity. In the case of the drum granulator, the standard deviation for sinter T.Fe and basicity were 0.6926 and 0.05449, respectively, as compared to 0.8902 and 0.2033 for the disc pelletizers. In addition, a single lattice method is proposed to optimize the particle-size distribution of the coke breeze to further improve sinter quality and reduce fuel consumption. The lattice method indicated that the optimum coke breeze to achieve maximum sinter tumble strength should consist of approximately 57.20%: −1 mm, 25.63%: 1–3 mm, 11.17%: 3–5 mm, and 6.00%: >5 mm particles. Given the international trend of increasing bed depth, Ansteel has successfully achieved a bed height of 1050 mm or more under its blend conditions, which typically contain 75% concentrates. Finally, some new iron ore agglomerations research is discussed. Full article

The metallurgical property of sinter is an important factor affecting the smooth operation of blast furnaces (BF), because it has a great impact on the permeability of BF and solid fuel rate. In order to promote the combustion of solid fuel and the mineralization of flux in sintering process, and eventually improve the strength of sintered ore, a series of investigation on segregation granulation by fuel and flux in coating were carried out, including the sinter pot experiments, the morphology analysis, and the discussion combine with phase diagram. The experimental results show that, (1) as the CaO increased from 0% to 40% and coke breeze increased from 0% to 100%, the sintering indices were improved, the tumble strength of sinter increased from 65.8% to 68.4%, the rate of qualified products increased from 77.4% to 81.0%, and the micro-strength of sinter increased from 68.7% to 75.9%. (2) There are three reasons for the high strength of sinter by segregation granulation of fuel and flux in coating, (a) the complete combustion of solid fuel and release the heat, (b) the effective absorb heat and mineralization of flux, and (c) the improvement of fluidity of bonding phase. The outcomes of the present work may provide a new method to improve the strength of sintered ore and give some reference for better understanding segregation granulation process and using it in actual operation. Full article

The metallurgical industry is seeking raw material substitutes more and more intensively in order to replace materials traditionally used in pig iron production. Research has been conducted on the use of char obtained from waste car tires via a pyrolysis process in an iron ore sintering process. The char obtained from car tires could be a potential substitute for some of the coke breeze used in the iron ore sintering process. However, the Zn and S content of the char is a major technological issue. This paper presents the results of research conducted to assess the possibility of substituting coke breeze with a commercial char from waste tires. The experiments were carried out in a laboratory stand capable of sintering 200 kg of sintering blend. The results obtained show that it is possible to replace 10 %m/m of coke breeze with waste tire char without any technological danger for sintering lines. The application of waste tire char in metallurgical processes is an example of actions that form part of the circular economy and also of the appropriate use of anthropogenic resources that are technologically available. Full article

In the iron-ore-sintering process, the use of biomass charcoal instead of coke breeze can reduce the emission of flue gas pollutants and alleviate the energy crisis of fossil fuels. However, the direct application of biomass charcoal to iron ore sintering is bound to affect the sinter properties. The effects of biomass charcoal addition on the sintering ore properties and flue gas pollutants emission were studied through sintering cup and related performance test experiments. Meanwhile, the influence mechanism of biomass charcoal instead of coke breeze on iron ore sintering was expounded. The experimental results show that with an increase in biomass charcoal, the vertical sintering rate increased, the internal pore structure developed rapidly, and the pollutant emission decreased gradually. When the biomass charcoal content was less than 40%, the sinter strength and yield were stable and slightly improved with the increase in biomass charcoal. When the biomass charcoal content was higher than 40%, the metallurgical properties of sinter degraded sharply, making it difficult to meet the production requirements. The comprehensive effect of biomass charcoal on the sinter suggests that the suitable biomass charcoal addition was 40%; under this condition, the reduction in SO₂ and NO_x was 28.2% and 25.7%, respectively. Full article

Carbon monoxide is the major hazardous component in flue gas exhausting from the iron ore sintering. This study aims to reduce the CO emission by changing the sinter parameters by sintering pot tests; specifically, the sinter quality, CO concentration, and total emission in sintering flue gas were analyzed in detail. The sinter strength properties, including the shatter index and the tumble index, are analyzed by the sintering pot test and the sintering flue gas discussion. The results show that the CO emission can be suppressed by modifying the sinter parameters, such as carbon content, coke breeze and coal breeze ratio, water addition, and sintering negative pressure. The good sinter parameters with the lower CO emission are 2.8% carbon content and 7.5% water in the sintering mixture. A higher coke breeze to coal breeze ratio, or only coke breeze fuel in the sinter mixture, is beneficial for the lower CO emission with a negative fan pressure of −12 kPa. Full article

When the briquetting process of fine-grained material takes place in the roller press unit, the pressure reached is over a hundred megapascals. This parameter is a result, among other factors, of the geometry of a compaction unit and also the properties of the consolidated material. The pressure of the unit is not constant and the changes in value depend on a given place on the molding surface. By the process of generating different types of pressure on the surface of briquettes, their compaction is different as well. The distribution of temperature on the surface of the briquettes may determine the pressure used locally on them. Nevertheless, the distribution of stress in the briquetting material is still a subject of scientific study. However, it is known that the pressure exerted on the briquette is different for different compaction systems. The article includes authors’ further thermography studies on the classical pillow-shaped briquetting process (instead of the saddle-shaped ones that were previously conducted) of four materials (calcium hydroxide and water mixture, mill scale, charcoal fines and starch mixture, as well as a mixture of EAFD, scale, fine coke breeze, molasses, and calcium hydroxide). Immediately after the briquettes left the compaction zone, thermal images were taken of them, as well as forming rollers. Thermograms that were obtained and the variability of temperature at characteristic points of the surface of pillow-shaped briquettes were analyzed. They showed differences in temperature on the surface of briquettes. In all four cases, the highest briquette temperatures were recorded in their upper part, which proves their better densification in this part. The temperature differences between the lower and upper part of the briquettes ranged from 1.8 to 9.7 °C, depending on the mixture. Full article

Most of the air pollutants in the steel industry come from the sintering process, and the air pollutants produced by the sintering process mainly come from the sinter fuel (coke breeze). The S and N content of biomass fuel is low; therefore, biomass fuel is used instead of coke breeze for sintering to reduce the emission of the sinter flue gas pollutants. However, the use of biomass fuel reduces the sintering layer temperature, which results in the deterioration of the sinter properties. In order to ensure the quality of sintering base on biomass fuel, the thermodynamic calculation and related experiments were carried out, the effects of different basicity, MgO and Al₂O₃ content on the formation of low melting point minerals in sintered mixture were studied, and the suitable composition of sintered mixture was determined in this paper, so as to reduce the liquid phase formation temperature of sinter and increase in biomass fuel addition, which provided theoretical support for the application of biomass fuel in sintering. Experimental results indicate that the suitable conditions for the low-temperature sintering were a basicity of 2.0, and MgO and Al₂O₃ contents of 1.0% and 1.8%, respectively. Under this condition, more biomass fuel can be used to replace coke breeze, and the emission of flue gas pollutants can be greatly reduced. Full article

The article presents results of the research on the use of chars produced during pyrolysis of residual biomass as a substitutional fuel in the iron ore sintering process. Such an approach allows to implement circular economy and industrial symbiosis to the iron and steel branches. The effect of the substitution of conventional coke breeze fuel used in sintering on final sinter quality and emission was examined. With regard to productivity, fuel consumption, and properties of the sinter it was shown that the share of tested biochars in fuel may be kept at 10, and up to 30 wt.%, depending on the biochar type. It was observed that with the use of the biochars, the content of iron oxide in the sinter decreased, which was advantageous. Moreover, the sinter obtained in the presence of biochars was characterized with better strength and abrasion than the sinter obtained with coke breeze-based fuel, improving the final product quality. The presence of biochar influenced the raw exhaust gas composition and resulted in a slight increase of organic and inorganic carbon compounds content, while the amount of sulfur oxides was noticeably decreased. It was concluded that the biochars may be applied in the sintering process at established share in the fuel stream. Full article

The sinter process of iron ore with biomass carbon instead of coke breeze as fuel was investigated via thermodynamic analysis in this paper through a comparison of sinter composition indexes, metallurgical properties, and pollutant emissions. Straw charcoal was used in this paper, and its replacement does not adversely affect the composition index of iron ore, namely Fe, FeO, basicity, S, nor the metallurgical properties, namely reduction degradation index and reduction index. However, the replacement has a great effect on the emissions of pollutant gases, including SO₂, NOx, CO, and CO₂. The thermodynamic analysis result shows that emissions of pollutant gases produced in the sinter process significantly decrease by using straw charcoal instead of coke breeze in sinter. The sintering maximum temperature has a great influence on sintering technical indicators. The best sintering maximum temperature is between 1300 and 1400 °C, where sinter ore with high quality can be obtained. Full article