Specialized metallurgical processes – compositions for use therei – Processes – Consolidating metalliferous material by agglomerating,...
Patent
1999-03-11
2000-12-19
Andrews, Melvyn
Specialized metallurgical processes, compositions for use therei
Processes
Consolidating metalliferous material by agglomerating,...
75962, 75 1041, C22B 120
Patent
active
06162280&
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for the thermal transformation of organic substances and of materials containing organic substances in a two-layer sintering process, wherein, after ignition of the first layer, a second layer is charged.
During the processing and machining of metallic materials, various fractions of oxidebearing metallic mixes are produced which are contaminated with water as well as with organic separating agents, lubricants or tensides.
In rolling processes, for example, rolling scale is produced as by-product. The rolling scale, which consists of fine particles and accumulated during the rolling process, enters the water circuit and is discharged in the form of rolling scale sludge. Rolling scale always bears organic separating and flotation agents and is thus a product to be disposed of and treated.
Depending on the production process, both the water content and the content of total hydrocarbons amount to 25 weight percent each. Because of this organic contamination, which is not easily degradable, recyclings poses a disposal problem. The thermal destruction of the hydrocarbons in connection with the processing of the partly oxidized metallic mixes, with the residual moisture being vaporized, provides an economical and environmentally compatible process engineering solution. In process control, however, it is to be ensured that no steam distillation of the highly volatile hydrocarbons occurs.
"K. Killmann und L. Schellberg: Mo glichkeiten der Aufarbeitung o lhaltiger Walzzunder-schla mme" (possibilities of processing oil-bearing rolling scale sludges), specialized literature: Drifte Duisburger Recycling-Tage, 1988, pp. 177-205, describes possibilities of process control in two-layer sintering processes, wherein, after charging of the first layer onto a sintering belt, this layer is ignited, charged onto the base layer formed in this way and also ignited.
In his doctoral thesis "Development and removal of aerosols in the double sintering process with rolling scale sludge charging", Duisburg Comprehensive University, 1989, pp. 1-3, 108, 109, Eckart Streich describes an improved process control of a sintering process controlled through the times of ignition. The ignition of the upper process is not started until the total waste gas system has reached operating temperature through the bum-off of the lower process, on the one hand, and the upper process should have its bumt-through point one minute before the lower process for safety reasons, on the other hand. This process, however, describes double sintering processes with the thickness of the sinter layers ranging between 200 and 400 mm. These embodiments have the disadvantage that layers formed in this way cause high pressure differences in the air compressor.
A process during which, after charging and ignition of a first sinter base layer, which may also contain solid fuels and volatile organic substances in iron-ore-bearing material, a second layer, which may optionally contain also solid fuels as well as vaporizable organic substances in an ore matrix, is charged and sintered is known from EP 0 437 407 A1. According to an embodiment, this second sinter layer is ignited with a time lag, the ignition time being determined by measuring the waste gas temperature and/or chemical analysis of the waste gases. In this process, sinter layers are formed that feature poor gas permeability owing to their composition and process control.
Accordingly, the technical problem of the invention is to create a process where the second layer is of higher sintering quality and where, moreover, improved waste gas values are achieved.
The technical problem is characterized in that the second layer containing organic substances is charged with a maximum thickness of 20% of the first layer and that thermal treatment of the second layer is started when the combustion zone of the first layer ensures combustion of the organic substances coming from the second layer and entering the combustion zone of the first layer, following the pressure difference, is at le
REFERENCES:
patent: 5382279 (1995-01-01), Anderson, II
W. Gebert, et al., "PCDD/F Emission Reduction for Sinter Plants", Steel Times, vol. 223, No. 6, Jun. 1995, Surrey, Great Britain, pp. 220-222.
Lehner Johann
Pammer Oskar
Schollnhammer Heinz
Stiasny Hans
Trimmel, deceased Wolfgang
Andrews Melvyn
Voest-Alpine Indstrienlagenbau GmbH
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