AU5936190A - Process for reducing the cyanide content of a solution - Google Patents
Process for reducing the cyanide content of a solutionInfo
- Publication number
- AU5936190A AU5936190A AU59361/90A AU5936190A AU5936190A AU 5936190 A AU5936190 A AU 5936190A AU 59361/90 A AU59361/90 A AU 59361/90A AU 5936190 A AU5936190 A AU 5936190A AU 5936190 A AU5936190 A AU 5936190A
- Authority
- AU
- Australia
- Prior art keywords
- solution
- cyanide
- ammonia
- process according
- aeration
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 title claims description 43
- 238000000034 method Methods 0.000 title claims description 38
- 230000008569 process Effects 0.000 title claims description 29
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 90
- 229910021529 ammonia Inorganic materials 0.000 claims description 35
- 238000005273 aeration Methods 0.000 claims description 16
- 239000003795 chemical substances by application Substances 0.000 claims description 14
- 238000005660 chlorination reaction Methods 0.000 claims description 14
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 9
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical group ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 claims description 4
- 230000026030 halogenation Effects 0.000 claims description 4
- 238000005658 halogenation reaction Methods 0.000 claims description 4
- 230000002140 halogenating effect Effects 0.000 claims description 2
- 230000003472 neutralizing effect Effects 0.000 claims description 2
- 238000005201 scrubbing Methods 0.000 claims description 2
- 239000000243 solution Substances 0.000 description 35
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 13
- 239000000460 chlorine Substances 0.000 description 13
- 238000012360 testing method Methods 0.000 description 13
- XLJMAIOERFSOGZ-UHFFFAOYSA-M cyanate Chemical compound [O-]C#N XLJMAIOERFSOGZ-UHFFFAOYSA-M 0.000 description 12
- 229910052801 chlorine Inorganic materials 0.000 description 11
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 11
- 239000002351 wastewater Substances 0.000 description 9
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 8
- 238000007792 addition Methods 0.000 description 8
- 239000007789 gas Substances 0.000 description 8
- 239000003153 chemical reaction reagent Substances 0.000 description 7
- 230000006378 damage Effects 0.000 description 7
- 230000003647 oxidation Effects 0.000 description 6
- 238000007254 oxidation reaction Methods 0.000 description 6
- 239000005708 Sodium hypochlorite Substances 0.000 description 4
- 239000001569 carbon dioxide Substances 0.000 description 4
- 229910002092 carbon dioxide Inorganic materials 0.000 description 4
- XLJMAIOERFSOGZ-UHFFFAOYSA-N cyanic acid Chemical compound OC#N XLJMAIOERFSOGZ-UHFFFAOYSA-N 0.000 description 4
- 230000007062 hydrolysis Effects 0.000 description 4
- 238000006460 hydrolysis reaction Methods 0.000 description 4
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 4
- 238000005903 acid hydrolysis reaction Methods 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- WQYVRQLZKVEZGA-UHFFFAOYSA-N hypochlorite Chemical compound Cl[O-] WQYVRQLZKVEZGA-UHFFFAOYSA-N 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 2
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 2
- 150000001412 amines Chemical class 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000003518 caustics Substances 0.000 description 2
- 229910001902 chlorine oxide Inorganic materials 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- QDHHCQZDFGDHMP-UHFFFAOYSA-N Chloramine Chemical compound ClN QDHHCQZDFGDHMP-UHFFFAOYSA-N 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 238000003556 assay Methods 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- KXZJHVJKXJLBKO-UHFFFAOYSA-N chembl1408157 Chemical compound N=1C2=CC=CC=C2C(C(=O)O)=CC=1C1=CC=C(O)C=C1 KXZJHVJKXJLBKO-UHFFFAOYSA-N 0.000 description 1
- 238000003889 chemical engineering Methods 0.000 description 1
- 239000012320 chlorinating reagent Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 150000001913 cyanates Chemical class 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000005187 foaming Methods 0.000 description 1
- 150000004820 halides Chemical class 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 150000002825 nitriles Chemical class 0.000 description 1
- 230000020477 pH reduction Effects 0.000 description 1
- GKKCIDNWFBPDBW-UHFFFAOYSA-M potassium cyanate Chemical compound [K]OC#N GKKCIDNWFBPDBW-UHFFFAOYSA-M 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000004291 sulphur dioxide Substances 0.000 description 1
- 235000010269 sulphur dioxide Nutrition 0.000 description 1
- 239000001117 sulphuric acid Substances 0.000 description 1
- 235000011149 sulphuric acid Nutrition 0.000 description 1
- DHCDFWKWKRSZHF-UHFFFAOYSA-L thiosulfate(2-) Chemical compound [O-]S([S-])(=O)=O DHCDFWKWKRSZHF-UHFFFAOYSA-L 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Physical Water Treatments (AREA)
Description
TITLE: PROCESS FOR REDUCING THE CYANIDE CONTENT OF A SOLUTION
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for reducing the cyanide content of a solution.
The use of an alkaline aqueous solution of a cyanide salt for recovery of gold and/or silver values from ores, tailings and wastes has been well known and documented for a long period. While this process is well known and widely used for such precious metal recovery it is also to be understood that the waste water streams from such processes contain cyanide in solution which could be dangerous if allowed to enter the environment and particularly the water supply.
For this reason, waste aqueous process streams from gold treatment plants using alkaline cyanide solutions as the leachant must meet specific composition limits before they are discharged into the environment. In particular, the total cyanide and free cyanide concentrations must be below the maximum limits set by local, state and federal licensing authorities.
Similar requirements are imposed on the effluent discharged from cyanide production plants and from other industrial processes some of which produce waste water streams containing other species notably ammonia as well as cyanide ions.
2. Discussion of the Prior Art
A number of processes have been proposed to bring about the chemical breakdown of the total and free cyanide components of typical effluent streams. Some of the processes have been patented and several are presently used on the commercial scale.
High temperature hydrolysis brings about the total destruction of the cyanide ion, but the high temperatures and extended retention times required makes this process inefficient in cost terms. Some chemical reagents convert
the cyanide ion only to cyanate. In many localities, discharge of cyanate is not permitted. Further destruction of cyanate may be inefficient or costly in reagent consumption terms, or in fact require a different chemical reagent.
The complexity of cyanide destruction is compounded by the presence of other species in solution that interfere with the destruction mechanism and/or substantially increase the capital and operating costs. One such species is dissolved ammonia.
Treatment of an effluent or processing liquor containing, for example, an equivalent concentration of cyanide ions and dissolved ammonia, by the standard cyanide destruction methods is unsatisfactory in terms of additional reagent consumption, increased capital and operating costs and/or incomplete cyanide destruction. These methods include the use of hydrogen peroxide, chlorine, chlorine/calcium hydroxide, hypochlorite, or sulphur dioxide.
The applicants are aware, for example, of a proposal described in Australian Patent Application 73261/81 (PCT International Publication Number W082/00288) for removing cyanide ions from solutions. This process provides for adjusting the solution to a pH of at least about 11 and to a halide content at least equivalent to the cyanide concentration. Electrolysis is performed using intense agitation of the electrolyte to result in deposition of solid carbon on the anode. Electrolytic methods generally require a readily available source of cheap electricity for economic operation and this is not always available in remote areas. Further, this proposal does not deal with any dissolved ammonia also present in the waste water stream.
Australian Patent Application 17053/88 (PCT International Publication Number WO 88/08408) relates to a method for separating by aeration a component such as cyanide from a liquid containing the component. The method comprises passing the liquid through an array of aeration columns arranged in stages so that the liquid flowing from one column
in a first stage is divided into two or more streams which are introduced into separate aeration columns in a successive second stage. However this process is likewise unsuitable for use in remote areas and does not effectively deal with any dissolved ammonia present in the waste water system.
Australian Patent Application 76929/81 relates to the chlorination of waste water containing ammonia, cyanide and phenol. This method involves adding a chlorinating compound to the waste water in a first vessel at pH 8.5 to 10, passing the waste water to a second vessel at pH 6 to 8 and controlling the addition of the chlorinating compound in response to the redox potential in the second vessel so as to maintain the redox potential at +625 millivolts to +750 millivolts. This method requires close monitoring of redox potentials and is specifically directed at waste water containing phenol as well as ammonia and cyanide contaminants.
SUMMARY OF THE INVENTION It is accordingly an object of the present invention to provide in one embodiment an improved process for reducing the cyanide content of a solution containing both cyanide and dissolved ammonia.
We have now found that the cyanide concentration of an effluent or process stream containing both cyanide and dissolved ammonia can be lowered to a level acceptable for discharge by a combination of steps. Accordingly, the present invention provides in one embodiment a process for reducing the cyanide content of a solution containing both cyanide ions and dissolved ammonia, comprising the following consecutive steps:
(a) adding a halogenating agent to the solution while maintaining the pH of the solution at greater than 7;
(b) removing ammonia from the solution by aeration;
(c) acidifying the solution to a pH of less than 7;
(d) substantially neutralising the solution; and
(e) removing the ammonia from the solution by aeration.
We have found that this combination of steps is effective in terms of both capital and operating costs and suitable for use in remote locations.
In step (a) the pH may be between 11 and 12 and most preferably about 12. The preferred reagent for raising the pH in step (a) and/or step (d) is sodium hydroxide.
In step (c) the preferred pH is less than 5 and most preferably from 3 to 4.
In step (d) the pH of the substantially neutralised solution may be about 7 and most preferably in the range 6 to 7.
The ammonia may be removed from the solution by aeration in the form of air stripping. Removed or stripped ammonia is preferably collected in a suitable gas scrubbing system.
The halogenation agent is preferably a chlorination agent. The chlorination agent may be any agent capable of generating and/or liberating chlorine in aqueous solution. Chlorine gas and agents capable of generating and/or liberating chlorine gas in the solution are particularly preferred for use as halogenation agents in accordance with the present invention. Hypochlorites such as sodium hypochlorite have been found suitable for use as chlorination agents in accordance with the present invention.
Where the chlorination agent is added in the form of gaseous chlorine the addition to the liquor may be achieved by means of a suitable gas sparging or bubbling system to oxidise the cyanide to cyanate.
In the process provided by the present invention, cyanide is converted by oxidation in step (a) to cyanate, which in step (c) is hydrolysed to ammonia and carbon dioxide. The carbon dioxide is readily removed from the reaction system. Step (c) may be considered as an acidification and hydrolysis step for converting the cyanate ion from the substantially ammonia free solution produced in step (b) to produce ammonia and carbon dioxide.
Steps (d) and (e) have the effect of re-neutralising the liquor derived from step (c) followed by removing the
dissolved ammonia produced by the acid hydrolysis of the cyanate ion. The final tail solution should be low in ammonia and contain little if any cyanide.
Each step may be carried out at temperatures close to ambient temperature (typically 15-30°C) and does not require the use of exotic materials of construction, nor the use of complex chemical engineering principles.
The present invention uses the effective combination of various known processes, none of which on its own, or in any other combination, would achieve the results achieved by the present invention by carrying out the present process, sequentially involving steps (a), (b), (c), (d) and (e). The process thus provides a unique method having substantial and unexpected advantages for treatment of waste waters.
More importantly, because the oxidation of cyanide to cyanate and the removal of dissolved ammonia are carried out separately, reagent consumption is minimised. This particularly applies to step (a), where tests show that complete oxidation of cyanide to cyanate is achieved by addition of typically 1.05 times the stoichiometric requirement of the halogenation agent.
Another significant advantage of the present process is that decomposition of cyanate to ammonia and carbon dioxide does not require the use of costly reagents.
EXAMPLES
The present invention is further described in the following non-limiting examples of illustrative embodiments. Example 1 Initial laboratory scale testing of individual steps in the process of the invention were carried out to demonstrate under controlled conditions the operation of individual steps. A. Examples of the Oxidation Step
As the source of chlorine, the laboratory testwork used as a chlorinating agent a solution of sodium hypochlorite with an equivalent free chlorine content of 13.1 g/L as determined
by titration against standard thiosulphate solution.
A solution (200 mL) containing 1000 ppm of cyanide ion (as sodium cyanide) and 1000 ppm of ammonia was treated with the above solution of sodium hypochlorite and the cyanide concentration was measured by ion selective electrode as a function of the added equivalent chlorine. In Test 1, shown in Table 1, the weight of chlorine sufficient to oxidise the amount of cyanide present in the solution to cyanate ion, was 0.54 g. The pH was 11.9-12.2 during the test.
Table 1
Test 1: Oxidation of Cyanide (1000 ppm) to Cyanate with
Chlorine in the presence of Ammonia (1000 ppm)
Chlorine Added Cyanide Concentration
(gms) (gms)
0.26 311
0.39 136 - 0.50 37
0.52 17
0.55 6
0.59 0
Test 2 was carried out in the same way as Test 1 except that the initial solution was 100 mL in volume and contained 2000 ppm of cyanide ion and 2000 ppm of ammonia.
Table 2
Test 2: Oxidation of Cyanide (2000 ppm) to Cyanate with
Chlorine in the presence of Ammonia (2000 ppm)
Chlorine Added Cyanide Concentration
(gms) (gms)
0.26 547
0.39 241
0.50 64 0.52 29
0.55 6
0.59 2
B. Examples of the Hydrolysis Step
As a pure source of cyanate ion, a solution of 3.1 g/L potassium cyanate was used.
In Test 3, 200 mL of this cyanate solution was treated with sufficient sulphuric acid solution to maintain pH 3.0 at room temperature. The increase in ammonia concentration as hydrolysis of cyanate proceeded was measured by specific ion electrode. The results are shown in Table 3.
Table 3
Time (min)
1
5
20
60
Test 4 was carried out in the same way as Test 3 except that the pH was maintained at pH 3.5
Table 4
Test 4: Hydn
Time (min)
1
5
20
60
105
Example 2
A test run was carried out on a prepared aqueous solution containing 2,000 mgm NH3 per litre and 1200 mgm CN~ per litre to simulate a waste process stream from an industrial process
containing both cyanide ions and dissolved ammonia, (a) Chlorination:
The solution was subjected to chlorination to oxidise all CN~ to CNO" using the minimum CI2/OCI" possible.
It was believed that a sharp rise in redox would occur at the 100% stoichiometric CI2 addition point i.e. where CN~ concentration < 1 ppm.
The pH during the chlorination was held at 11.9- 12.0.
Chlorination was conducted by the addition of sodium hypochlorite. The results are summarised in Table 1 which shows that the stoichiometry at the mV rise was 100-105%.
TIME PH CN" (mins) (ppm)
0 11.4 1,210 2
10 11.9
21
24 716
29
37 11.9
38
47 384
53
78 11.9
79
95 105 100 129 11.9 18 134 148 11.9 157 161 174 12.0 176
189 0.3 191 + 8 12.0 192 108 206 + 20 12.0
(b) First Aeration
The CNOVNH3 mixture formed at around pH 12 in the chlorination step was passed through a packed column to remove the bulk of the NH3 to atmosphere leaving a weak NH3/CNO- solution.
The column used for all aerations was a 7 m length of 300 mm Class 6 PVC pipe packed with 5 m of 1" tellerettes. Air flow was produced by fan suction with flow measured at the fan outlet using a digital turbine anenometer. Liquor flow was visually monitored via flow meter but physically measured by level change in the head tank.
Liquor flow was produced by a centrifugal pump running at - 2800 rpm.
Ammonia removal was 89% at an Air:Liquor ratio of 4900:1.
The area specific flow rates were:
Liquor = 0.55 lm'^sec--*- Air = 162 m min--*-m~*2
Exit gas assays via drager tubes indicated 450 ppm v/v NH3.
The drager tube reacts to NH3 and other basic species (amines) in the sample gas, e.g. monochloramine, etc.
(c) (d) Acid Hydrolysis
The solution formed in the first aeration was made acidic to hydrolyse all CNO~ to NH4+ followed by caustic addition to raise the pH, converting NH4+ to NH3.
CNO- destruction was very rapid, probably less than 30 minutes.
The acid and caustic requirements for this stage were about 6 kg H2S0 m~3 for pH 12 to pH 3 and 5 kg NaOH in"3 to raise pH from 3 to 12. It was noted that some foaming occurs when pH falls below 7. (e) Second Aeration
The NH3 in the neutralised solution formed in the acid hydrolysis stage was removed to the atmosphere in a second aeration.
Ammonia removal during this second aeration was 92% at an Air:Liquor Ratio of 4750:1.
The area specific flow rates for this second aeration were: Liquor = 0.57 lm~2sec_1
Air = 164 m3min~-*-m"~2
The drager tube sampling method was again used on the exit gas giving an indicated 200 ppm v/v NH3 in the exit gas. Calculations based on air and liquor flows and the reduction in the solution NH3 levels predict 170 ppm v/v NH3 in the gas phase. Hence, the drager tubes appear to give realistic figures in this stage, at least. The conclusion which can be drawn from this example is that chlorination of the CN~ can be achieved by near stoichiometric addition of chlorine. A small excess seems necessary, possibly due to reaction with ammonia at the lower CN~ levels.
Stripping of NH3 from the alkaline solutions is very efficient with good tail solutions being obtained. Chlorinated amines in the exit gas would not appear to be a problem especially with accurate chlorination dosing control. Cyanate conversion is very rapid indeed and thus is not a problem.
While it has been convenient to describe the invention herein in relation to particularly preferred embodiments, it is to be appreciated that other embodiments and arrangements are also considered as falling within the scope of the invention. Various modifications, alterations, variations and/or additions to the embodiments and arrangements described herein are also considered as falling within the scope and ambit of the present invention as defined by the claims.
Claims (8)
1- A process for reducing the cyanide content of a solution containing both cyanide ions and dissolved ammonia, comprising the following consecutive steps:
(a) adding a halogenating agent to the solution while maintaining the pH of the solution at greater than 7;
(b) removing ammonia from the solution by aeration;
(c) acidifying the solution to a pH of less than 7;
(d) substantially neutralising the solution; and (e) removing the ammonia from the solution by aeration.
2. A process according to Claim 1 wherein the aeration steps comprise air stripping for removal of ammonia from the solution.
3. A process according to Claim 1 or Claim 2 wherein the halogenation agent is a chlorination agent.
4. A process according to Claim 3 wherein the chlorination agent is chlorine gas.
5. A process according to Claim 4 wherein the chlorine gas is generated in solution.
6. A process according to any preceding claim wherein the pH is maintained at a level of between 11 and 12 during step (a) .
7. A process according to any preceding claim wherein sodium hydroxide is used to raise pH in step (a) and/or step (d).
8. A process according to any preceding claim wherein ammonia removed from the solution is collected in a gas scrubbing system.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU59361/90A AU619998B2 (en) | 1989-07-05 | 1990-07-05 | Process for reducing the cyanide content of a solution |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AUPJ5097 | 1989-07-05 | ||
AUPJ509789 | 1989-07-05 | ||
AU59361/90A AU619998B2 (en) | 1989-07-05 | 1990-07-05 | Process for reducing the cyanide content of a solution |
Publications (2)
Publication Number | Publication Date |
---|---|
AU5936190A true AU5936190A (en) | 1991-01-17 |
AU619998B2 AU619998B2 (en) | 1992-02-06 |
Family
ID=25632335
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
AU59361/90A Ceased AU619998B2 (en) | 1989-07-05 | 1990-07-05 | Process for reducing the cyanide content of a solution |
Country Status (1)
Country | Link |
---|---|
AU (1) | AU619998B2 (en) |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4070281A (en) * | 1974-08-05 | 1978-01-24 | Asahi Kasei Kogyo Kabushiki Kaisha | Method for treating waste water |
US4105545A (en) * | 1976-09-14 | 1978-08-08 | Treadwell Corp. | Process for removing cyanide-containing components from aqueous media |
ZA817073B (en) * | 1980-10-30 | 1982-09-29 | Uss Eng & Consult | Chlorination of wastewater |
-
1990
- 1990-07-05 AU AU59361/90A patent/AU619998B2/en not_active Ceased
Also Published As
Publication number | Publication date |
---|---|
AU619998B2 (en) | 1992-02-06 |
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