Effect of SO2 Crossover on Hydrogen and Sulfuric Acid Production in a PEM Electrolyzer

2019 ◽  
Vol 19 (10) ◽  
pp. 67-75 ◽  
Author(s):  
John A. Staser ◽  
J. W. Weidner
Keyword(s):  
Sulfuric Acid ◽  
Acid Production ◽  
Sulfuric Acid Production ◽  
Pem Electrolyzer

Pilot-Scale Bioleaching of Metals from Pyritic Ashes

2017 ◽  
Vol 262 ◽  
pp. 147-150
Author(s):  
Elina A. Vuorenmaa ◽  
Jarno Mäkinen ◽  
Tero Korhonen ◽  
Raisa Neitola ◽  
Anna H. Kaksonen
Keyword(s):  
Sulfuric Acid ◽  
Acid Production ◽  
Pilot Scale ◽  
Solution Ph ◽  
Mineral Salts ◽  
Sulfuric Acid Production ◽  
Stirred Tank Reactors ◽  
Working Volume ◽  
Guideline Values ◽  
The Government

Solid waste from sulfuric acid production may contain relatively high levels of metals such as Fe, Zn, Co, Cu and As that are harmful if inappropriately disposed of in the environment, but may be a valuable resource if metals can be recovered. The objective of this research was to investigate the pilot-scale acid bioleaching of metals from pyritic ashes, originating from the roasting of pyrite ores for sulfuric acid production and consisting mainly of hematite. Bioleaching was carried out at 25 °C in pilot-scale continuously stirred tank reactors (CSTR), with 50 L working volume in mineral salts medium supplemented with trace elements, 1 % (w/v) elemental sulfur and with pyritic ash pulp densities 10 % and 20 %. The reactors were inoculated with a mixed culture of iron- and sulfur-oxidising acidophiles containing Acidithiobacillus (At.) ferrooxidans, At. thiooxidans/albertensis, At. caldus, Leptospirillum ferrooxidans, Sulfobacillus (Sb.) thermosulfidooxidans, Sb. thermotolerans and some members of Alicyclobacillus genus. Metal leaching yields from pyritic ashes in the CSTR after 32 days were 54.6-56.7 % Cu, 41.7-43.2 % Zn, 1.7-1.8 % Co, 3.0-5.4 % As and 0.3-0.5 % Fe. Solution pH decreased during the experiment from 2.9 to 1.9-2.2. Elemental analysis using X-ray fluorescence showed that the contents of metals, except for As, in the leach residue were below the higher guideline values given in the Government decree on the assessment of the soil contamination and remediation needs by the Ministry of the Environment, Finland. Bioleaching facilitated the extraction of metals from pyritic ashes and the mitigation of environmental risks related to the residue disposal for other metals except for As.

Synthesis of a Mixed Catalyst for Sulfuric Acid Production Using Various Wastes

2003 ◽  
Vol 76 (11) ◽  
pp. 1769-1771
Author(s):  
L. A. Nefedova ◽  
S. A. Lavrishcheva ◽  
E. I. Dobkina ◽  
S. M. Kuznetsova
Keyword(s):  
Sulfuric Acid ◽  
Acid Production ◽  
Sulfuric Acid Production ◽  
Mixed Catalyst
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