Cyanide treatment

Various treatment technologies are used at the iron and steel plant for recycle system water treatment prior to recycle and reuse, or end-of-pipe wastewater treatment prior to discharge to surface water or a POTW. The physical/chemical treatment technologies extensively used include equalization, tar removal, free and fixed ammonia stripping, cooling technologies, cyanide treatment technologies,... 

Substituting nonpolluting cleaners for cyanide cleaners can avoid cyanide treatment entirely. For a 7.6L/min rinsewater flow, this means a savings of about USD 18,400 in equipment costs and USD 10/kg of cyanide treatment chemical costs. In this case, treatment chemical costs are about four times the cost of the raw sodium cyanide cleaner. 

Self-monitoring for cyanide must be conducted after cyanide treatment and before dilution with other streams. Alternatively, samples may be taken of the final effluent, if the plant limitations are adjusted based on the dilution ratio of the cyanide waste stream flow to the effluent flow. 

Except as specifically provided in the U.S. CFR, any existing point source subject to this subpart must achieve the effluent limitations shown in Table 9.19 which represents the degree of effluent reduction attainable by applying the BAT. Alternatively, for the metal finishing industrial facilities with cyanide treatment, and upon agreement between a source subject to those limits and the pollution control authority, the amenable cyanide limit shown in Table 9.20 may apply in place of the total cyanide limit specified in Table 9.19. No user subject to the provisions of these regulations shall augment the use of process wastewater or otherwise dilute the wastewater as a partial or total substitute for adequate treatment to achieve compliance with this limitation. 

PSNS, shown in Table 9.25. Alternatively, for industrial facilities with cyanide treatment, and upon agreement between a source subject to these limits and the pollution control authority, the amenable cyanide limit shown in Table 9.26 may apply in place of the total cyanide limit specified in Table 9.25. 

Water Treatment of sample with NaOH and hypophosphite passage through silver filter (free cyanide) treatment in photo cell prior to filter for total cyanide and selective oxidation for cyanides not amenable to chlorination (CNATC) Flame AAS or graphite furnace AAS 2 ng/mL (flame AAS) 0.06 ng/mL (graphite furnace AAS 107 (free cyanide), 90.4 (CNATC), 98.1 (total cyanide) Rosentreter and Skogerboe 1992... 

Scott JS. 1985. An overview of cyanide treatment methods for gold mill effluents. Conf. Cyanide and Environment, Tuscon, AZ, December 1984. Published by Geotechnical Engineering Program, Colorado State University, Fort Collins, CO, 307-330. 

System IV is a pretreatment technology for water containing cyanide and heavy metals including chromium, nickel, zinc, lead, cadmium, and copper. The technology precipitates a range of heavy metals there is no need to install separate pieces of equipment for individual metals. A cyanide treatment system expansion option is available for waste streams that also contain cyanide. System IV is not offered commercially. 

After the crude product is separated the filtrate obtained from the cyanide treatment previously described is diluted to about 500ml with water, boiled for five minutes with approximately fig of charcoal, and filtered while hot. The boiling filtrate is treated with aqueous cadmium chloride, as described, to remove the remaining octacyanomolybdate from the excess thiocyanate present. Although this batch of cadmium salt is not so pure as the material obtained the first time, further purification is not necessary for the decomposition step that follows. 

A XANES study of the Au/A1203 system has shown that Au3+ was reduced to Au° in helium at 623 K, and that sodium cyanide treatment dissolved some 80% of the gold the remaining Au + was however reduced by a second helium treatment.54... 

Botz, M., Cyanide Treatment Methods, Mining Environmental Management, 9 (3), 28-30, May 2001. 

Since the isolation of succinate dehydrogenase from cyanide-treated particles 146), a considerable amount of work has been done on the effect of cyanide on succinate dehydrogenase. Treatment of particles with cyanide diminishes succinate-PMS reductase activity by about 50% and causes a large increase in the apparent K,n of the dye. These effects are prevented by succinate 189). The effect of cyanide is more drastic on electron transfer from succinate to methylene blue or the respiratory chain. These reactions are almost completely destroyed by cyanide. Experiments with partially purified succinate dehydrogenase showed, however, that cyanide treatment did not alter the PMS reductase activity 190). The reactive species has been shown to be CN, which binds strongly to succinate dehydrogenase 189-191). According to Zanetti et... 

The accumulated ACC appears to be transported to the shoot, where it induces more synthesis of ACC which is converted to ethylene and cyanide. Treatment of isolated shoots with ACC via the vascular system stimulated ACC synthase activity and ethylene and cyanide production [7,37,49,51]. Cyanide was formed as a coproduct of ethylene in the oxidation of ACC, catalyzed by ACC oxidase [14,52]. While quinclorac-induced increases of ABA and hydrogen peroxide are not enough to elicit herbicidal effects [7], cyanide levels in the grass shoot tissue accumulated according to the herbicide concentration and application time and closely correlated with phytotoxicity... 

Complex 376 can be prepared from enantiomerically pure rhenium precursor 381. The former can be deprotonated at low temperatures initiating the [2,3]-sigmatropic rearrangement to diastereomerically pure homoallylic sulfide complex 377. After S-alkylation, cyanide treatment releases the S ligand as product 379. As an extension of this work the authors showed that iron and ruthenium complexes can be used, too [219]. 

As a classical technique for the synthesis of aromatic cyanides treatment of the corresponding halides with CuCN has to be cited (Rosenmund-von Braun reaction). It is carried out at 15C1-250 C, either without any solvent at all, or using pyridine or quinoline, which also operate as complexing agents for the CuCN. Other heavy metal cyanides or hexacyanoferrates have been used in principle, but their... 

Fig. 9.10. Transmission electron micrograph of gold spheroids before and 1 h after cyanide treatment, a no cyanide, b ...

Fig. 9.13. Transmission electron micrographs of gold nanorods, aspect ratio 18, before (a) and 24 h after (b) cyanide treatment. Reprinted with permission from [62], Copyright (2002) American Chemical Society.

The above reaction occurs rapidly at pH levels below 3. Because the acidic properties of ferrous sulfate are low at high dilutions, acid must be added for pH adjustment. The ferrous sulfate reducing process generates large volumes of sludge and thus its use is rare in large-scale treatment facilities. In addition, the use of ferrous sulfate to treat chromate wastes containing cyanide results in the formation of very stable ferrocyanide complexes, which prevent subsequent effective cyanide treatment. 

Amyl nitrite has been used as a vasodilator drug, a diagnostic agent, and a cyanide treatment adjunct it is an abused inhalant. Butyl nitrite is an abused inhalant. Isobutyl nitrite is an ingredient of various incenses or room odorizers, and it is also used as a jet propellant and in the preparation of fuels. It is an abused inhalant. 

Metallurgical Practice.— Leaching of sands by percolation was very widely used in the United States up to a few years ago in the cyanide treatment of gold ores, and is still largely used in the Transvaal. The reason for its decline was the successful development of processes for the treatment of slimes at lower costs which resulted in the plants treating all their material as slime instead of separate treatments as before for sands and slimes. The question of removing the leached material from the tanks is handled in a number of different ways. 

In the case of the direct electrochemical approach, while the electrolysis conditions are less severe, the selection of the appropriate electrode material is still very important, and further reading on the use of stainless steel [93], platinum [94], graphite [95], doped Sn02 [92], doped Pb02 [86, 87, 96], and so on, is suggested. The economic viability of the electrochemical treatment approach is influenced in no small way by the cost and lifetime of the anode material this can easily make or break the field implementation of the process. Some authors have used high-surface area, porous anodes for cyanide treatment in order to combat the problems of mass-transport limitations so evident at cyanide concentrations below 100 ppm [88]. That system consists of a reticulated vitreous carbon porous anode that was activated for cyanide oxidation by the deposition of some copper oxide. The process looks very promising at the laboratory scale,... 

In contrast to mammalian experience, rapid resumption of aerobic metabolism by the insects after cyanide treatment was detrimental to the insect. However, the surprising deleterious effects appeared to be due to one of the products of the aerobic metabolism of cyanide (B34) rather than to oxygen or peroxide formation. The inhibition of catalase by cyanide appeared to have no obvious relationship to the enhancement of toxicity by oxygen. 

In the process involving hydrogen cyanide, treatment of process waste water becomes an issue of environmental concern in addition to the air pollution control. 

Reaction of quinoxalin-2(lH)-one 4-oxide (33) with potassium cyanide gives the cyanoquinoxalinone 35. The latter compound may be converted into the amide 36 by treatment with hydrogen chloride in acetic acid. The amide can be converted into the corresponding acid by reaction with warm aqueous acetic and sulfuric acids. A smilar sequence of reactions is not possible with the N-methyl compound 34 because in this case aqueous potassium cyanide treatment gives the quinoxalinedione 37. ... 

---