Use of Bentonite and Organic Binders in the Briquetting of Particulate Residues from the Midrex Process for Improving the Thermal Stability and Reducibility of the Briquettes

Abstract

With the aim of achieving sufficient reducibility and thermal stability of briquettes for reuse as feedstock in the Midrex direct reduction process, a defined mixture of residues from the Midrex process is briquetted with an organic binder and bentonite. In the first step, briquetting tests are conducted to investigate the influence of water and binder content on the mechanical properties of the briquettes. Suitable briquettes are then used for reduction tests, where mechanical properties under Midrex‐relevant conditions are considered. The tests show that briquettes with an organic binder (with and without bentonite) are not stable under Midrex‐relevant conditions, whereas briquettes with a mixture composition with 5 wt% bentonite and 5 wt% water are. This can be justified on the basis of microscopic images. Bentonite favors the sintering mechanisms occurring between the particles. The organic binders decompose thermally and carbon remains, which prevents sintering. The reduction tests show that oxygen release from the briquettes occurs more slowly than for iron oxide pellets. However, the residual mixture already contains reduced material (Femet of briquettes with bentonite 28.1 wt%), so less oxygen has to be removed. Furthermore, a small briquette format (volume 10 cm3) shows better reduction behavior compared to bigger briquettes.

Effect of Top Gas Recycling Technology on the Softening, Melting and Dropping Behavior of V–Ti Bearing Burden in COREX Process

“…1) Therefore, in the context of the urgent transformation of global development to zero carbon emission, non-blast furnace ironmaking technologies such as COREX are being vigorously developed. [2][3][4][5] Our previous research has proposed and confirmed that COREX process has a huge advantage in smelting V-Ti bearing burden due to the pure oxygen (without N 2 ) blown into the tuyere. 6) However, COREX also has some problems of insufficient gas flow, excessively high tuyere temperature and high fuel ratio compared with blast furnace, which affects its operation and commercial application.…”

A Review of Pyrolysis Technologies and the Effect of Process Parameters on Biocarbon Properties

“…Peach starch [171] Sodium carboxymethylcellulose [171] Cassava starch [172] Asphalt [173] Pyrolysis oil [174][175][176][177] Molasses [178] Distillers dry grain [178] Crude glycerol [169] Lignosulfonate [169,179] Lignin [168] Lignin powder [167] Pinecones [167] Pyrolytic Lignin [180] Protein, starch, lignin, and molasses [181] Waste cooking oil [182] Deionized water [183] Bentonite [184][185][186][187] Ash [188] Limestone [165] Clay [165] Magnesium oxide [165] Calcium oxide [165] Calcium hydroxide [168] Sodium hydroxide [168] Attapulgite [189] Sodium silicate [165] Magnesium chloride [165] Waste Plastic [190] Kaolin-bentonite-sodium humate [191] Corn straw-sodium hydroxide-MgCl/MgO [191] Coal tar pitch phenolic resins [191] Coal tar pitch and molasses [192] Kang et al [176] reported that when pyrolysis oils are used as a binder, they improve surface morphology and the pellets' physical stability. More precisely, these oils improve pellet drop resistance and compression strength.…”

Development of a Sustainable Metallurgical Process to Valorize Copper Smelting Wastes with Olive Stones-Based Biochar

“…This material is used as a binder in the preparation of the pellets. It is considered a suitable inorganic material for the agglomeration of different materials with a similar particle size [19].…”