Dust Briquettes Research Articles

Investigation on cooperative desulfurization efficiency for bearing carbon stainless steel dust briquettes chromium and nickel recovery process

During the stainless steel making process, Fe-Cr-Ni of lower sulfur content can be recycled from stainless steel dust (SSD) by briquettes reduction. An investigation of cooperative desulfurization efficiency for bearing carbon SSD briquettes reduction process is conducted. First, slag amount prediction model is established through corundum crucible erosion behavior in order to analyze the desulfurization efficiency. Next, the effects of carbon amount, CaF2 amount, silicon ferrous, basicity and feeding modes on the desulfurization rate and the sulfur distribution ratio are analyzed. Furthermore, sulfur distribution ratio prediction model between SSD briquettes and molten iron is originally established in the principle of thermodynamic equilibrium. Results show that basicity, CaF2, silicon ferrous and carbon amount could promote the desulfurization rate and sulfur distribution ratio. When simultaneously adding iron ingot and SSD briquettes, feeding mode has a higher desulfurization rate and better metal/slag separation than when adding iron ingot prior to SSD briquettes. During the experiment, desulfurization rate varies from 55% to 70% and the sulfur distribution ratio results range from 2 to 10. The sulfur distribution ratio prediction results greatly match with experimental results implying that the desulfurization rate analysis method through corundum crucible erosion behavior is more accurate.

Feasibility study of coconut coir dust briquette

This research work was conducted on economic feasibility of briquette made of coconut coir dust mixed with rice husk at different ratio. This study sought to assess the physical properties and calorific value of briquette and to establish the demand and willingness of potential users to substitute rice husk briquette and firewood. It was observed that briquette made from mixed coconut coir dust and rice husk at the ratio of 1:2 and 1:1 had desirable properties as compared to rice husk briquette. The percent of shatter indices, density, percent of resistance to water penetration, degree of densification and calorific value of briquette of mixing ratio 1:2 were found 99.75, 1.52gm/cc, 87.5, 11.35 and 4043 kcal/kg and of mixing ratio 1:1 were found 99.82, 1.48gm/cc, 87.5, 10.84 and 3657 kcal/kg, respectively. In case of rice husk briquette, the above values were 99.21, 1.40gm/cc, 75, 10.66 and 3537 kcal/kg, respectively. The production costs of mixing ratio 1:2 and 1: 1 were 3.27 Tk/kg and 3.10 Tk/kg, respectively which were lower than that of rice husk briquette. In partial budget, the substitution propositions among the selected briquettes indicated that coconut coir dust briquette of mixing ratio 1:1 appeared as the most impressive one.J. Bangladesh Agril. Univ. 12(2): 369-376, December 2014

Conversion of Entire Dusts and Sludges Generated During Manufacture of Stainless Steels into Value Added Products

During manufacture of stainless steel, for each ton of product, nearly 50 kg of dusts from electric arc furnace (EAF), argon-oxygen decarburizing converter (AOD), grinding shop & rolling mills are generated. In addition, nearly 25 kg of filter cake is produced from pickling lines sludge. These contain valuable as well as hazardous metals and their gainful utilization/disposal has been subject of intense research. Wide varieties of technologies have been developed and some of them have been successfully used on industrial scale. The technologies developed are of two types. One way is to recover metals present in the dust and sludge and the other is to immobilize their hazardous components followed by their utilization as ceramic material or landfill. Such processes include direct injection of dust in the metal bath of EAF, injection in a coke bed reactor, pelletizing with coal or coke fines and reducing them in a rotary kiln/rotary health furnace to obtain hot DRI/HBI or briquetting of dust followed by smelting in submerged arc furnace (SAF). The conversion of entire dusts and sludge by SAF is energy intensive. While there is increasing focus on utilization of dusts and sludge by internal or external processing, a significant amount of generated dusts and sludge still find their way to land fill. Recognizing that the composition of dusts/sludges emanating from EAF, AOD, rolling mills and pickling lines differ vastly, study was undertaken for a more efficient and cost effective approach for recycling them for metal recovery. Since AOD dust contains high percentage of lime, its utilization in SAF entails addition of quartz and high energy consumption. This paper describes lab scale trials in induction furnace with AOD dust briquettes containing different proportion of carbonaceous reductant. These trials indicated that very good recovery of metallic elements is possible by use of AOD dust briquettes containing high carbon in EAF. On the other hand, briquetting of zinc rich EAF dust, followed by charging it in SAF, enriched zinc oxide powder and master alloy containing valuable metals were obtained as useful products. The paper describes combining AOD dust, mill scale, grinding dust and low sulfur filter cake in one stream and clubbing EAF dust which is rich in zinc with high sulfur filter cake. The former category was briquetted with carbonaceous reductant and recycled in large scale plant trials in a 50 ton EAF and the latter was briquetted and smelted in SAF to produce master alloy and enriched zinc oxide powder. In this manner, the entire quantity of dusts and sludges could be profitably utilized along with conservation of valuable metallic elements.

Mechanical, physical and chemical properties of saw dust briquette

The present study deals with determination of physical, mechanical and combustion characteristics like mass, density, compressive strength, shearing strength, moisture content, total ash content, fixed carbon, volatile matter, gross calorific value of Sawdust briquette. Briquette quality is evaluated mainly by briquette density. Briquette density is very important from the viewpoint of manipulation, burning speed, briquette durability, etc. During our research, theoretical analyses of parameters which have an impact on briquette quality were conducted. The sawdust sample produced using super-70 piston press machine. The compression test and shear test were conducted for three sawdust sample using compression testing machine. For quality and durability evaluation of the manufactured briquette the density and strength properties were determined. To determine the calorific value and proximate analysis of the briquette using the tests carried out in the lab.

Separation of Metal Nugget from Self-reduced Product of Coal Composite Stainless Steel Dust Briquette

To efficiently recycle valuable metals such as chromium and nickel in stainless steel dust, a research was made to separate metal nugget included chromium and nickel from self-reduced products of coal composite stainless steel dust briquette, here is defined as a CCSB. Metal nuggets and slag were formed in self-reduction process of CCSB. After reduction, a large amount of C3S and a little C2S existed in slag due to its high basicity. However, C2S content was increased by solidification of oxide melt in slag, and then, it was much increased by decomposition reaction of C3S as reduced products were kept up at low temperature. The transformation of β C2S→γ C2S was occurred in slag during cooling as slag was shattered due to volume expansion, and then separation of metal nugget was achieved. The effect of basicity on separation of metal nugget was considered. Thermodynamics equilibrium calculations and non-equilibrium cooling calculations were carried out on chemical reactions in CCSB, and separation mechanism of metal nugget and the effects of holding time and temperature on separation were investigated. The optimum holding temperature and time were 1100°C and 15 min, respectively. Recovery ratio of iron, chromium and nickel were 92.5%, 92.0%, and 93.1, respectively. Metal nuggets were separated from self-reduced product of CCSB without using any auxiliary materials. This separation method can indicate one innovative process for stainless steel dust comprehensive utilization.

Effect on Environment by Burning Different Agricultural Waste

Many of the developing countries produce huge quantities of agro residues but they are used inefficiently causing extensive pollution to the environment. The major residues are rice husk, coffee husk, coir pith, jute sticks, bagasse, groundnut shells, mustard stalks and cotton stalks. The objective was to analyze the burning characteristic of paddy straw briquettes, cotton plant waste, corn sticks, saw dust briquette, wood and paddy straw, these were burnt and combustibles percentage, CO (ppm) and NO (ppm) were noted by multi gas analyzer. By analyzing the flue gases coming out during burning of these fuels, then plotting the graph of different parameters like combustibles, CO and NO which were obtained during burning of fuels with respect to time. Also the ash content left after burning was recorded. On combining all these parameters briquettes proves out to be clean source of energy, briquettes burn slowly giving out a constant amount of heat and less amount of combustibles as compared to other agricultural residue.

Physical Quality of Some Biomass Briquettes

This paper deals with the effect of material and concentration of binders on the physical quality of biomass briquettes. The briquettes were prepared using tree leaves, saw dust and wheat straw. Two binding materials namely, molasses and sodium silicate at varying concentration were used in the preparation of briquettes. The Saw dust and wheat straw briquettes could not be formed when concentration of binder was below 10% whereas formation of tree leaves briquettes was possible even without use of any binding materials. Sodium silicate was found a better binding agent than molasses for briquette preparation. The bulk density of briquettes of tree leaves, saw dust and wheat straw with molasses as binder was observed as 3.5, 6.3 and 3.8 times of the bulk density of respective raw materials. The study revealed that among all types of briquettes, saw dust briquettes with sodium silicate at 25% concentration were better in terms of compressive strength, shattering resistance, bulk density and calorific value and hence better for transportation, storage and for burning purposes.