Vanadium removal from Stretford purge. Final technical report
The SRC-I Process effectively refines high-sulfur coal, upgrading the coal quality and recovering the sulfur as a by-product. A Claus sulfur recovery unit recovers most of the sulfur in the process offgas, and a Beavon Stretford unit removes the residual sulfur in the Claus tail gas. A vanadium salt, a hazardous chemical, is the component of the Stretford solution that oxidizes the H/sub 2/S. Sulfur-containing salts of various oxidation states are formed during the process, requiring periodic blowdown or purging of the Stretford solution in order to prevent precipitation of the salts. The Stretford purge stream, although representing less than 0.4% of the equalized flow to the wastewater treatment system, accounts for virtually all of its vanadium content. Chemical oxygen demand (COD) is also very high, accounting for almost 10% of the COD content of the feedwater to the wastewater treatment system. ICRC undertook a program to evaluate how effectively available vanadium precipitation technology, i.e., ferrous sulfate addition, treated the Stretford purge stream, and what effects the treated effluent had on downstream processes. The results of this study show that pH adjustment to 10.2 with lime could reduce the vanadium in the Stretford purge by one-half. Addition of FeSO/sub 4/ at a Fe:V molar ratio of 4.9 effectively removed the vanadium by 92%, which is an acceptable result. The dosage was 20 times the stoichiometric amount based on FeV/sub 4/O/sub 9/ and 10 times the amount based on Fe(VO/sub 3/)/sub 2/, which was much higher than reported in the literature for synthetic wastes. It has been hypothesized that the organics present in the actual waste and the oxidzation state of vanadium were the causes of the apparent discrepancy. 7 references, 1 figure, 7 tables.
- Research Organization:
- International Coal Refining Co., Allentown, PA (USA)
- DOE Contract Number:
- AC05-78OR03054
- OSTI ID:
- 6772828
- Report Number(s):
- DOE/OR/03054-69; ON: DE84013931
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BLOWDOWN
CHEMICAL COMPOSITION
SRC PROCESS
STRETFORD PROCESS
VANADIUM COMPOUNDS
PRECIPITATION
BIOCHEMICAL OXYGEN DEMAND
CHEMICAL OXYGEN DEMAND
COAL LIQUEFACTION
DEMONSTRATION PLANTS
PH VALUE
RECOVERY
SULFUR
WASTE WATER
ELEMENTS
HYDROGEN COMPOUNDS
LIQUEFACTION
LIQUID WASTES
NONMETALS
OXYGEN COMPOUNDS
SEPARATION PROCESSES
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPOUNDS
WASTES
WATER
010405* - Coal
Lignite
& Peat- Hydrogenation & Liquefaction