Development of a method using Euglena gracilis to evaluate toxicity of free cyanide and strong metal cyanide complexes related to mining

2013 ◽  
Author(s):  
Homa Teimouri Sichani
Keyword(s):  
Euglena Gracilis ◽  
Free Cyanide ◽  
Metal Cyanide ◽  
Cyanide Complexes

scholarly journals A Study of Residual Cyanides and Potential Stabilities in Tailings Storage Facility of Gold Mining Operation

2015 ◽  
pp. 11-18 ◽  
Author(s):  
Suwanit Parinyachet ◽  
Quanchai Leepowpanth
Keyword(s):  
Gold Mining ◽  
Mining Operation ◽  
Strong Acid ◽  
Weak Acid ◽  
Processing Plant ◽  
Storage Facility ◽  
Free Cyanide ◽  
Metal Cyanide ◽  
Acid Generation ◽  
Cyanide Complexes

The study aimed to investigate residual cyanides and their potential stabilities in tailings from a gold processing plant deposited in the Tailings Storage Facility (TSF) of a gold mining site. For this purpose, several samples of tailings were taken from the recently abandoned TSF to a depth of 2.5 meters, representing 1 to 2 years old tailings. The samples were analyzed for pH, metals, residual cyanides, and Net Acid Generation Test (NAG test). The results showed that, in all samples, pH values were neutral to slightly alkaline. Fe concentrations were relatively high (22,800-35,000 mg kg-1) indicating that Fe can readily react with free cyanide (CN-) to form iron cyanide complexes (strong metal cyanide complexes). The residual cyanide concentration in tailings was found to be very low; free cyanide (CNFree), weak acid dissociable cyanide (CNWAD), strong acid dissociable cyanide (CNSAD) and total cyanide (CNT) were in the range of 0.16-0.64, 0.37-1.06, 1.96-3.89 and 2.33-4.95 mg kg-1, respectively. Cyanides in the tailings were predominantly strong metal cyanide complexes being more stable to dissociate. Total cyanide (CNT) concentration was quite low compared with Thailand’s environmental regulations for soil quality standards andwere environmentally insignificant. The NAG test for all samples revealed that NAG pH was in the range of 5.02-6.10 and NAG was in the range of 0.08-0.31 kg H2SO4t-1indicating all samples have low or non-acid forming potentials. The findings indicated a potential to form a high proportion of strong metal cyanide complexes in the tailings, which is difficult to dissociate and releasehigh toxic cyanide to the environment.

Highly active double metal cyanide complexes: Effect of central metal and ligand on reaction of epoxide/CO2

2007 ◽  
Vol 18 (7) ◽  
pp. 887-890 ◽  
Author(s):  
Xing Hong Zhang ◽  
Shang Chen ◽  
Xian Ming Wu ◽  
Xue Ke Sun ◽  
Fei Liu ◽  
...  
Keyword(s):  
Central Metal ◽  
Metal Cyanide ◽  
Highly Active ◽  
Cyanide Complexes

scholarly journals Bacterial Consortiums Able to Use Metal-Cyanide Complexes as a Nitrogen Source

Proceedings ◽  
2018 ◽  
Vol 2 (20) ◽  
pp. 1284
Author(s):  
María Isabel Igeño ◽  
Daniel Macías ◽  
María Isabel Guijo ◽  
Rubén Sánchez-Clemente ◽  
Ana G. Población ◽  
...  
Keyword(s):  
Nitrogen Source ◽  
Industrial Effluents ◽  
Free Form ◽  
Bacterial Strains ◽  
Pseudomonas Pseudoalcaligenes ◽  
Metal Cyanide ◽  
Biodegradation Process ◽  
Cyanide Complexes ◽  
Cyano Compounds

Most cyanide-containing industrial effluents also contain other cyano-derivatives and high amounts of metals and metal-cyanide compounds. For this reason, the biotreatment of these wastes requires the use of microorganisms capable to degrade all these different cyano-compounds and to tolerate metals. Pseudomonas pseudoalcaligenes CECT 5344 is a cyanotrophic bacterium capable of metabolize cyanide in its free form, but it is not very efficient at degrading metal-cyanide complexes. Therefore, for the optimization of the cyanide biodegradation process it is essential to find and characterize new bacterial strains, capable of assimilating metal cyanide-complexes, to complement the capacities of P. pseudoalcaligenes CECT 5344.

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