The Strength and Density of Green and Reduced Briquettes Made with Iron Ore and Charcoal

Abstract

Composite briquettes or pellets consisting of iron ore, carbon, and a binder are a source of direct reduced iron (DRI). In the handling of green and reduced briquettes, high strength is important to minimize briquette breakdown. The use of charcoal as a source of carbon, rather than coal provides a way of introducing renewable carbon into the ironmaking process. Composite briquettes were made with Australian hematite iron ore, low volatile charcoal and 2 % starch as a binder. The carbon-to-iron mass ratio was varied between 0.18 and 0.26. The green briquettes were heated to either 1300 or 1350°C for times varying from 3 to 15 min. After heating, the briquettes were tested for compressive strength, density, and the degree of iron metallization. The aim of the work was to determine the key strength forming features of the briquettes during heating and reduction. Dried green briquettes, made with a starch binder, were found to be very strong and required a force of at least 3800 N to yield under compression. After heating for 3 min, the briquettes lost strength rapidly before regaining strength at longer heating times of 10 and 15 min. Increasing the C/Fe ratio in the briquette mix decreased the strength and density, and increased the iron metallization of the heated briquettes. Briquette strength also increased with increasing time from 10 to 15 min and heating temperature from 1300 to 1350°C. These observations can be explained in terms of the distance between iron oxide particles in the briquette mix. At low C/Fe ratios, iron oxide particles will be relatively close together which facilitates the development of a connected slag network which acts as a binder and increases briquette strength.

The Analysis of the Morphology of the Saddle-Shaped Bronze Chips Briquettes Produced in the Roller Press

“…The information on the briquette external surfaces morphology can be very useful for the correct modeling or correction of forming tools cavities. Studies available in the literature describe mainly the compressive strength of briquettes in relation to their density [ 50 ], however, the influence of the quality of the obtained briquette surface on the local briquette density and its distribution has not been investigated so far. Therefore, the aim of this study was to obtain the information on the physical and mechanical properties of the external surfaces and the cross-sections of the investigated saddle-shaped briquettes produced in a roller press.…”

Briquetting of Fine‐Grained Residues from Iron and Steel Production Using Organic and Inorganic Binders

“…In the literature, there are mainly studies on the production of self-reducing or composite pellets with organic substances. [6][7][8][9][10][11][12][13][14][15] However, the addition of carbon usually lowers the strength of agglomerates. Therefore, briquettes normally contain less than 10 wt% carbon.…”

Synthesis and optimization of combustion of briquettes based on substandard brown coals of Kazakhstan deposits with multipolymer binders

“…According to the weight loss of the TGA curves, it can be assumed that the evaporation of polyethylene begins at temperatures close to 350-500ºC, the breaking of polyolefin chains starts at lower temperatures at the foam 250-385ºС. This is due to the decomposition of the whole polymer chain with the simultaneous release of some gaseous products 41,42 .…”