Steel industry wastes

The concentration of up to 100 mg/kg of cadmium in phosphate minerals increases the contamination of soil with cadmium. Steel industry wastes, recycled into fertilizers for their high levels of zinc (essential to plant growth), can include the toxic metals lead, arsenic and cadmium. The most common toxic elements in this type of fertilizer are mercury, lead, and arsenic. 

Treatment of Industrial Wastes. The alkaline nature and inexpensive price of lime make it ideal for treatment of acid waste Hquors (6), including waste pickle Hquids from steel plants, wastes from metal plating operations, eg, chrome and copper plating, acid wastes from chemical and explosives plants, and acid mine wastewaters. 

Marchand, D. Waste Gas Collection on Electric. Arc Furnaces BFI Research and Development During the Last 20 Years. In APCA Specialty Proceedings-Air Pollution Control in the Iron and Steel Industry, Chicago, IL, Apr. 1981, pp. 42-57. 

These three steps all produce significant amounts of waste. First, as discussed earlier, the nitration process results in the production of spent sulfuric acid. In the past the company had been able to sell much of this material to the coke and steel industries but declining demand meant that the acid now required disposing of, at additional cost. At the time green catalytic nitration technology was becoming available with clay, zeolite and lanthanide catalysts all providing possible alternatives to the use of sulfuric acid (see below). Improved selectivity to the desired para-isomer is an added benefit of some of these catalytic systems. However on the... 

California Steel Industries, Inc., located in Fontana, CA, reclaimed wastes to increase profits and address water use issues. The facility, a steel mill, is situated in an area that does not have a ready supply of process water. Also, the offsite recycling facility used to dispose of spent process pickle liquor was soon to become unavailable. As a result of these concerns, the company constructed an onsite recycling facility designed to recover ferrous chloride for resale and to reuse water and hydrogen chloride for use in steel processing operations. Environmental benefits include the recovery and resale of 20 to 25 t/d of ferrous chloride, 13,440 L/d of hydrogen chloride, and 49,200 L/d of water. In addition, corporate liability was minimized because spent liquor was no longer sent to a disposal facility. 

The marketable slag makes up about 10 to 15% of the steel output, or 210 to 300 lb/t of steel.1 BOF dust and sludge generated during the cleaning of gases emitted from the BOF represent two of the three largest-volume wastes typically land disposed by the iron and steel industry. 

The iron and steel industry needs to opt for technologies that help to either prevent or reduce the generation and discharge of process wastes. The various preventive measures to be adopted for reducing the environmental impacts are as follows ... 

Patzelt, R.R. and Hassick, D.E., Dewatering of steel-mill sludges by belt-press filtration, Section 13—Steel and Foundry Wastes, in Proceedings of the 39th Industrial Waste Conference, Purdue University, 469-485, 1984. 

Sources of lead in surface water or sediment include deposits of lead-containing dust from the atmosphere, waste water from industries that handle lead (primarily iron and steel industries and lead producers), urban runoff, and mining piles. 

Stationary sources Waste incineration Steel industry Recycling plants Energy production Municipal solid waste, clinical waste, hazardous waste, sewage sludge Steel mills, sintering plants, hot-strip mills Non-ferrous metals (melting, foundry Al, Cu, Ptx, Zn, Sn) Fossil fuel power plants, wood combustion, landfill gas... 

In most countries, solid waste containing metals such as neutralization sludge from the plating industry and flue dust from the metal and steel industries is currently collected and dumped in landfill, where it constitutes a perpetual toxic threat to the environment and a waste of resources. The alternatives to this landfill disposal are either to reduce the rate of discharge at source by an individually designed recovery process or to separate and recover the metals from the collected waste in a centrally located facility. A presumption for a centrally located facility would be that companies with metals in their effluents require treatment of their total wastewater streams. This could be accomplished through the relatively simple process of neutralization, which requires minor investment in sedimentation tanks and dewatering equipment and involves relatively modest operation costs. 

Chemically bonded advanced ceramic materials with high wear and corrosion resistance for agricultural and industrial applications from steel and other industry waste. 

Vanadium leaches soil from a large number of diverse sources, including waste effluents from the iron and steel industries and chemical industries. Phosphate industries are also a major source of vanadium pollution because vanadium becomes soluble along with phosphoric acids when rock phosphates are leached with sulfuric acid. Vanadium is present in all subsequent phosphoric acid preparations, including ammonium phosphate fertilisers, and is released into the environment along with them. Other sources of vanadium pollution are fossil fuels, such as crude petroleum, coal and lignite. Burning these fuels releases vanadium into the air, which then settles in the soils. 

Improved energy efficiency is even more important in underdeveloped nations. In China, for example, the energy use of building conditioning could be cut in half. Similarly, the energy use of China s power plants, refineries, and cement and steel industries could all be reduced by 25-50%. Chapter 2 of this volume describes specific optimization and energy conservation techniques that can be adopted immediately to eliminate such energy waste in the various industries. 

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