US 4,341,641 A · Process for treating cyanide and cyanate containing wastewaters

Abstract

A process for treating a cyanide and cyanate-containing aqueous influent such as a wastewater stream is provided. A two-stage method is included for destroying a cyanide-containing influent which comprises; (a) introducing said cyanide-containing influent into a first ozone-contacting zone; (b) contacting said influent in said first zone with a second ozone-containing gas, at least a portion of said second ozone-containing gas comprising a first ozone-depleted gas withdrawn from a second contact zone to form a first cyanide-depleted effluent and a second ozone-depleted gas; (c) introducing said first cyanide-depleted effluent into a second ozone-contacting zone; (d) contacting said effluent in said second zone with a first ozone-containing gas to form a second cyanide-depleted effluent and a first ozone-depleted gas; (e) withdrawing said first ozone-depleted gas from said second contact zone; and (f) withdrawing said second cyanide-depleted effluent from said second zone. A single stage method is also provided in this invention. Both single stage and double stage embodiments employ a turbine-gas injector in each ozone-contacting zone to accomplish a high mass transfer of the ozone-containing gas to the influent. In both the single stage and double stage method, the cyanide-depleted effluents may be recycled to the aqueous influent stream prior to its introduction to either the first or second ozone-contacting zone or to the contacting zones themselves to destroy cyanides and cyanates in these effluents. This destruction is accomplished by allowing residual ozone or other oxidizing species in the recycled effluent to react with the cyanide/cyanate species and reducing influent concentrations by diluting the influent entering the contacting zones while at the same time obtaining lower ozone-containing gas to liquid (G/L) ratios. In a further embodiment of this invention a method for treating a cyanate-containing influent formed by oxidizing cyanide by any of the above described methods is provided which comprises further multiple ozone-treatment stages.

Claims38

Dependent claims

A process for treating an aqueous cyanide-containing influent consisting essentially of:

(a) providing an ozone-contacting zone having an operating turbine gas injector associated therewith, said injector comprising:
a hollow casing extending into said zone having an enlarged section at the lower end thereof, said enlarged section having an annular elongated gap which communicates with said zone;
a shaft rotatably mounted in said casing;
a turbine-bladed impeller rotor mounted on said shaft and extending into said enlarged section, said rotor having a liquid intake section;
means for rotating said shaft;
and
a gas inlet communicating with said casing above said enlarged section;
(b) introducing said influent to said ozone-contacting zone;
at least a portion of said influent being introduced to said liquid intake section;
(c) introducing an ozone-containing gas to said gas inlet;
(d) mixing by spinning said impeller at least a portion of said influent with said ozone-containing gas in said enlarged section to form a stream of bubbles of ozone-containing as in said influent and injecting said stream into said zone;
(e) withdrawing a cyanide-depleted effluent from said zone;
(f) combining at least a portion of said cyanide depleted effluent with said cyanide-containing influent;
and
(g) repeating steps (b) to (e).

12 more elements

A process for treating a cyanide-containing aqueous influent consisting essentially of:

(a) providing a first and second ozone contacting zone, each zone having an operating turbine gas injector associated therewith, said injector comprising:
a hollow casing extending into said zone having an enlarged section at the lower end thereof, said enlarged section having an annular elongated gap which communicates with said zone;
a shaft rotatably mounted in said casing;
a turbine-bladed impeller rotor mounted on said shaft and extending into said enlarged section, said rotor having a liquid intake section;
means for rotating said shaft;
and
a gas inlet communicating with said casing above said enlarged section;
(b) introducing said cyanide-containing influent into said first ozone-contacting zone, at least a portion of said influent being introduced to said liquid intake section;
(c) introducing a second ozone-containing gas into said gas inlet of said injector in said first zone, at least a portion of said second ozone-containing gas comprising a first ozone-depleted gas withdrawn from said second contact zone;
(d) mixing by spinning said impeller of said injector in said first zone at least a portion of said influent with said second ozone-containing gas in said enlarged section to form a stream of bubbles of said second ozone-containing gas in said influent and injecting said stream into said first zone to form a first cyanide-depleted effluent;
(e) withdrawing said first cyanide-depleted effluent from said zone;
(f) introducing said first cyanide-depleted effluent into said second ozone-contacting zone, at least a portion of said effluent being introduced to said liquid intake section of said injector in said second zone;
(g) introducing a first ozone-containing gas into said gas inlet of said injector in said second zone;
(h) mixing by spinning said impeller of said injector in said second zone at least a portion of said first cyanide-depleted effluent with said first ozone-containing gas in said enlarged section to form a stream of bubbles of said first ozone-containing gas in said effluent and injecting said stream into said second zone to form a second cyanide-depleted effluent and a first ozone-depleted gas;
(i) withdrawing said first ozone-depleted gas from said second contact zone;
and
(j) withdrawing said second cyanide-depleted effluent from said second zone.

14 more elements

A process for treating a cyanide-containing aqueous influent consisting essentially of:

(a) providing a first and second ozone contacting zone, each zone having an operating turbine gas injector associated therewith, said injector comprising:
a hollow casing extending into said zone having an enlarged section at the lower end thereof, said enlarged section having an annular elongated gap which extends into said zone;
a shaft rotatably mounted in said casing;
a turbine bladed impeller rotor mounted on said shaft and extending into said enlarged section, said rotor having a liquid intake section;
means for rotating said shaft;
and
a gas inlet communicating with said casing above said enlarged section;
(b) introducing said cyanide-containing influent into said first ozone-contacting zone, at least a portion of said influent being introduced to said liquid intake section;
(c) introducing a second ozone-containing gas into said gas inlet of said injector in said first zone, at least a portion of said second ozone-containing gas comprising a first ozone-depleted depleted gas withdrawn from said second contact zone;
(d) mixing by spinning said impeller of said injector in said first zone at least a portion of said influent with said second ozone-containing gas in said enlarged section to form a stream of bubbles of said second ozone-containing gas in said influent and injecting said stream into said first zone to form a first cyanide-depleted effluent;
(e) withdrawing said first cyanide-depleted effluent from said zone;
(f) introducing said first cyanide-depleted effluent into said second ozone-contacting zone, at least a portion of said effluent being introduced to said liquid intake section of said injector in said second zone;
(g) introducing a first ozone-containing gas into said gas inlet of said injector in said second zone;
(h) mixing by spinning said impeller of said injector in said second zone at least a portion of said cyanide-depleted effluent with said first ozone-containing gas in said enlarged section to form a stream of bubbles of said first ozone-containing gas in said effluent and injecting said stream into said second zone to form a second cyanide-depleted effluent and a first ozone-depleted gas;
(i) withdrawing said first ozone-depleted gas from said second zone;
(j) withdrawing said second cyanide-depleted effluent from said second zone;
(k) combining at least a portion of said second cyanide-depleted effluent with said cyanide containing aqueous influent;
and
(l) repeating steps (b) to (j).

16 more elements

Dependencies are inferred from the claim text.

Process for treating cyanide and cyanate containing wastewaters

Life of this patent

Process for treating cyanide and cyanate containing wastewaters

Life of this patent

Abstract

Claims38