Recovery of lime, sulfur, and iron from gypsum and pyrite wastes

Journal Article · Wed May 01 04:00:00 EDT 1996 · Industrial and Engineering Chemistry Research

DOI:https://doi.org/10.1021/ie950383n· OSTI ID:253765

Kutsovskaya, M L; Hepworth, M T ^[1]; McGaa, J R ^[2]

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1. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Civil Engineering
2. Bureau of Mines, Minneapolis, MN (United States)

Currently, gypsum and pyrite, two major wastes generated by the coal combustion industry, have to be land-filled. The feasibility of a new approach of recovery of lime, iron, and sulfur products from these wastes is discussed in the present work. By thermal decomposition of pyrite, 42% of the sulfur is recovered and pyrrhotite is produced. A thermodynamic analysis shows that the recovery of iron and lime from pyrrhotite and gypsum in a single-stage process is not feasible. Instead, the process has to consist of two subsequent stages. The first is the reduction of pyrrhotite with carbon in the presence of lime to produce iron, calcium sulfide, and carbon monoxide, followed by reaction of calcium sulfide with gypsum to produce lime and a concentrated sulfur dioxide stream. The kinetics of the reactions involved in the two-stage process is studied using thermogravimetric analysis. The reaction rates are favorable above 950C and depend on initial reagent concentrations. The effectiveness of magnetic separation of the Fe/CaS mixture is studied. The amount of sulfur in the magnetic fraction depends on the reaction temperature.

• OSTI ID: 253765
• Journal Information: Industrial and Engineering Chemistry Research, Journal Name: Industrial and Engineering Chemistry Research Journal Issue: 5 Vol. 35; ISSN IECRED; ISSN 0888-5885
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
CALCIUM OXIDES
CALCIUM SULFIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COAL INDUSTRY
GYPSUM
IRON
MAGNETIC SEPARATORS
MATERIALS RECOVERY
PYRITE
PYROLYSIS
PYRRHOTITE
SULFUR
TEMPERATURE DEPENDENCE
THERMAL GRAVIMETRIC ANALYSIS
WASTE MANAGEMENT