CA1331895C - System and method for the extraction of cyanide from tails liquor - Google Patents
System and method for the extraction of cyanide from tails liquorInfo
- Publication number
- CA1331895C CA1331895C CA000564951A CA564951A CA1331895C CA 1331895 C CA1331895 C CA 1331895C CA 000564951 A CA000564951 A CA 000564951A CA 564951 A CA564951 A CA 564951A CA 1331895 C CA1331895 C CA 1331895C
- Authority
- CA
- Canada
- Prior art keywords
- aeration
- liquid
- air
- column
- columns
- 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.)
- Expired - Fee Related
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/20—Treatment of water, waste water, or sewage by degassing, i.e. liberation of dissolved gases
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D21/00—Separation of suspended solid particles from liquids by sedimentation
- B01D21/01—Separation of suspended solid particles from liquids by sedimentation using flocculating agents
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D21/00—Separation of suspended solid particles from liquids by sedimentation
- B01D21/24—Feed or discharge mechanisms for settling tanks
- B01D21/2488—Feed or discharge mechanisms for settling tanks bringing about a partial recirculation of the liquid, e.g. for introducing chemical aids
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D21/00—Separation of suspended solid particles from liquids by sedimentation
- B01D21/30—Control equipment
- B01D21/305—Control of chemical properties of a component, e.g. control of pH
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2221/00—Applications of separation devices
- B01D2221/04—Separation devices for treating liquids from earth drilling, mining
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/16—Nitrogen compounds, e.g. ammonia
- C02F2101/18—Cyanides
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/10—Nature of the water, waste water, sewage or sludge to be treated from quarries or from mining activities
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/22—Nature of the water, waste water, sewage or sludge to be treated from the processing of animals, e.g. poultry, fish, or parts thereof
- C02F2103/24—Nature of the water, waste water, sewage or sludge to be treated from the processing of animals, e.g. poultry, fish, or parts thereof from tanneries
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Organic Chemistry (AREA)
- Physical Water Treatments (AREA)
- Treating Waste Gases (AREA)
Abstract
ABSTRACT
The invention relates to a method and system 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 aeration column in a first stage is divided into two or more streams which are introduced into separate aeration columns in a successive second stage. The method also comprises passing air through the aeration columns counter-current to the liquid to entrain at least a portion of the component in the air thereby to separate at least the portion from the liquid.
The invention relates to a method and system 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 aeration column in a first stage is divided into two or more streams which are introduced into separate aeration columns in a successive second stage. The method also comprises passing air through the aeration columns counter-current to the liquid to entrain at least a portion of the component in the air thereby to separate at least the portion from the liquid.
Description
1 33 1 ~95 SYSTEM ANC~ METHOD FOR THE EXTR~CTION OF
CYANIDE E'ROM ~AlLS LIQUOR
Thc present invention r~lates to a method and a system for treating by ~eration a liquid contai~ing a ... . .
component to separat~ th~e ~omponent from the liquid. In particular, the present invention relates to a method and 10 a 3ystem ~or tre~ting by aeration a liquid Gontnining - -cyanide to separate cyanid~ from the liq~id.
~t i9 known to flcrate ~ liquid to sep~rAte from e~e liquid any dissolved gases in the l~quid. For example, it is known to aerate liquid containing 15 dissolved cyanide to separate the cyanide from the liquid.
q'j One problem associated with known aeration techniques i9 that a considerable volume of air is required in proportion to the volume of liquid.
An object of the present invention is to alleviate the problem described in the preceding paragraph and to provide a more efficient and cost effective method and system for treating by aeration a liquid containing a component to separate the component from the liquid.
In a broad aspect, the present invention relates to a method of separating a component from a liquid containing the component, comprising passing the liquid downwardly through each aexation column in an array of aeration columns arranged in stages so that the liquid flowing from an outlet of one aeration column in a first stage is divided into two or more streams which are introduced into separate aeration columns in a successive second stage and passing air serially through each of the aeration columns in each stage counter-current to the liquid to entrain at least a portion of the component in - the air thereby to separate at least the portion of the component from-the liquid.
In another broad aspect, the present invention relates to a system for separating a component from a liquid containing the component, comprising a plurality of aeration columns to receive the liquid therethrough, the aeration columns arranged in a series of stages so that in use liquid which flows through one said aeration column in a first stage is subsequently divided into at least two separate streams and the streams are directed into separate aeration columns in a second stage downstream from the first stage, eàch aeration column having an inlet for spraying liquid downwardly through the column and an inlet for directing a stream of air upwardly through the column so that the liquid and the air flow in counter-current relationship and a means to direct air serially through _ . ., ~. .... .
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1 33 1 ~' 9 , -2a-each aeration column in each stage in counter-current relationship to the liquid to entrain the component in the air, thereby to separate the component from the liquid.
According to the present invention there iB
provided a method of separating by aeration a component from a liquid containing the component comprising, in a first stage, passing the liquid counter-current to a stream of air to entrain a portion the component in the air thereby to separate the portion from the liquid, ~ubsequently dividing the liquid into a plurality of divided portion~3, and, in a second stage, passing each divided portion counter-current to a stream of air so as to entrain a further portion of the component in the air -thereby to separate the further portion from the liquid. -Preferably, the component comprises cyanide.
Preferably, according to the present invention there is provided a method of separating by aeration cyanide from liquid containing cyanide, comprising:
(a) adjusting the pH of the liquid to be in the acidic ~-~
range to cause the formation of free hydrogen cyanide -~
gas in the liquid;
(b) passing the liquid through an array of aeration columns arranged in stages so that the liquid flowing from one aeration column in a first stage is divided into two or more streams which are introduced into separate aeration columns in a successive second stage; and - ~--,p~ ,.
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(c) passin~ air t~rough the aeration columns counter-current to the liquid to entrain the free hydrogen cyanide gas, thereby to separate cyanide from the liquid.
~ccording to the present invention therc is also provided a system for separating a component from a liquid containing the component, comprifiin~:
(a) a plurality of aeration columns to : t~, receive thc liquid therethrough, the aeration columns arranged in a series of stages so that, in use, liquid which flows through one said aerati.on column in a ~irst stage is subsequently divided into at least two separate streams and the streams are directed into lS separate said aeration columns in a second stage downstream from the first st~e: and ~) means to direct air t~rou~h the aeration columns counter-current to the liquid to entrain the component in the air, thereby to separate the component from the liquld.
~` Preferably, when the system is u~ed to sep~rate cyanide from a liquid, in accordance with the invention the system oomprises a means to adjust the pH of the liquid to be in tho acidic range to cause t~e formation 25 of free hydro~en cyanide ~as in the li~uid prior to the introduction of th~ liquid into the aeration columns.
The term "column`' is understood ~erein to mean any container or the like, suoh as an open ended tube which is adapted to receive liquid therein.
The term "aeration" i~ understood herein to mean a process in which a liq~id is exposed to th~ action of air or any other ~ration gas.
The invention is now descr~bed in moro detail with reference to a specific c~bodiment thereof. The 35 description is ~ade with reference to the acco~panying drawings, in which;
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~igure 1 is a schematic block diagram of a tailings treatment process in its entiret~; -Pigure 2 is a detailed schematic drawing showing the particular arrangement of the aeration 5 columns and c~ustic circulation tanXs used in the proccss;
Fi~ure 3 is a block diagram showing the principal of passing air through t~e aeration columns in a serial manner without changing the volume of air 10 relative to each aeration eolumn; and -~
Fig~re 4 is a detailed schematic diagram showing th~ manner in which air passes through a single pair of separation and absorption aeration col~mns counter-current ~ith the liquor And c~ustic solution.
The specific e~bodiment concerns a system and proces~ for treating tailings from an extraction plAnt for the reco~ory of gold or other minerals.
In. one known process for extracting gold fro~
its ore, cyanide is dissolved in water and ~he resultant 20 solution is used to leach gold from d~posits of ore. In t~c leaching process, some of the cyanide remains in the tailings or the residue f~om the. plant. The purpose of the system and process dcscribed herein is to treat the tailinqs so as to r~move suf~icient of the cyanide to 25 enabl~ the tailings to be disposed of in an environmentally satis~actory condition.
The system and procefis initially comp~ises ~orming a tails liquor from the tailin~s dump which is dccanted by known meAnS 1 and pumped to a mixing chamber 30 2~`
Acid Rtored in a bulk ac1d storage tank 3 is pumpQd by ~n acidification doaing pump to the chamber for AdmixtUrc with the tails liquor so as to adjust to thc pH
of the liquor into the acid rang~ thereby to eause th~
35 formation of free hydrogen cyanide gas which is retained in the liquor.
_ From th~ mixi~g chamber 2, the liquor is pumped into a sand-floc cohtact tank 4. Coagulant, ~locc~l~nt and make-up sand from respective s~orage tanks 5, 6 and 7 are added to the sand-floc contact tank 4. The mixtur~
S is agitated and flows h~ ~ravity to a constant density tan~ 8 The underflow from the const~nt density tank 8 is pumped to a ~yclone 9. The cyclone underflow is returned to the sand-floc contact tank 4 for re-use. The 10 cyclone overflow is directed to a settling pond 10 from which liquor is drawn off and returned to t~c sand-floc contact tank 4 and the liquid is transferred to pondage.
The liquor from the constant density tank B
flows by gravity through sand filters 12 and then is 15 pumped to a column 13a. The column 13a is a preliminar~
aeration column for the separation of cyanido from the liquor. In this re~ard, th~ liquor is sprayed into the column 13a a,nd flows downwardly therethrough counter-current to a stream of air directed upwardly 20 through thc column 13a. The stream of air is drawn fr~m the constant density tank 8 and has the effect of entraining a portion of the free hydrogen cyanide gas in the liquor. The air is drawn from the top of column 13a and is directed through an absorption column 13b for 25 ab~orption of the hydrogen cyanide gas into a caustic solution.
The liquo~, with a reduced cyanide concentration, which collects at ~he bottom of the oolumn 13a is pumped to an array of aeration columns, generally 30 identified by the numerall 14, to remove a ~urther portion of the c~anide in the liquor. The aeration column~ in thu array 14 are Arranged in ~ta~e* so that the liquid flowing from onc aeration column in a fir~t stage is divided into t~o strea~s which are introduced into two 35 s~parat~ aeration columns in a successive second staqe.
~he aeration columns in the array 14 are also arranged to . - , i'~_``~.. ,' . ' `~ ~ 33 1 ~5 receive therethrough alr in counter-current flow to the flow of liquor, thereby to entrain free hydrogen cyanide gas in the air. The array 14 of aeration columns i9 described in more detail hexcinafter.
The liquor. with a substantially red~ced cyanide concentration, which passes thro~gh the final ~tage of the array 14 of aeration columns, is conveyed to a final aeration colu~n 15. Thc liquor i~ passad downwardly through the aeration co~umn 15 counter-~urrent 10 to an upward flow of air drawn from the atmosphere.
The liquor from the final aeration column 15, being clean and substantially free of cyanide, is passed through columns 16 which Contain carbon to colloct any residual gold in t~e liquor. The liguor from the columns 15 16 is suitable ~or disposal. Such disposal may ~e by direct transfer to a tailings impoundment system or via A
pH correction stage 17 where a suitable reagent such as -~ -lime or caustic soda is added to rai~e the p~ of the l~quor t~ a level ~uitable for dischar~e into the 20 environment.
The array 14 of aeration columns is now described in more detail with reference to Figures 2 and 4. The array comprises a plurality of pairs of aeration columns 14a, 14b, ... 14c''' w~ich ar~ arranged in thre~
25 stages. The first stage comprises the pair oP aeratlon col~mns 14a, the second stagc comprises the pairs of aeration columns 14b, 14b' and the t~ird ~tage comprises the pairs of aeration columns 14c, 14c', 14c'' and 14c'''-Each pair af ae~ation columns 14a, 14b 14C''' compris~s, an aeration column 25 ~or use in connection with tho sep~ration of free hydro~en cyanidc gas from liquor by means of a counter-curren~ flow o~
air, and an aeration column 26 for use in connection with 35 the absorption of hydrogen cyanide ~as ~rom the air in~o a stream o~ caustic solution.
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.,, "", ~,, The separation column 25 and absorption column 2~ in each pair are separated ~y an intermediate air duct 29 which maintains liquor in separation column 25 and caustic solution in ~bsorption column 26 whilst al.lowing 5 air flow 27 to pass serially through bot~ columns fro~ an inlet air port 28 disposed in the separation column 2S to an outlet air port 30 disposed in the absorption ~olumn 26. In this manner air is passed serially through the columns 25, 26 in each pair.
The liquor i~ introduced in a spray through an inlet liquor port 31 disposed nuar the top of ea~h separntion ~olumn 25 and flows downwardly and is discharged through an outlet ].iquor port 33 near the ~ase of e~ch separation col~mn 25. Each separation column 2S
15 contains a bed of pao~ing material 32 s~spended theroin to promote dispersion of the downward flo~ of liquor and upward flow of air thereby to en~ance aeration of thc liquor ~nd,.as a consequence, to enhance entrainmcnt of the free hydrogen cyanide gas in the air.
: 20 Similarly, the caustic solution is introduced in a spray thro~gh a Gaustic inlet port 34 disposed ncar the top of each absorption column 26 and flows downwardly and is discharged through a ca~stic outlet port 36 disposed near the bas~ of ~ach absorption colu~n 26. In 25 addition, each absorption column 26 contains a bed of packing material 35 suspended ther~in to promote ., dispersion o the downward flow of caustic solution and upward flow of air thereby to cnhance aeration of the caustic solution and, as a consequ~nce, to enhance 30 absorption oF the hydrogen cyanide gas in the caust.io solution~
Th~ pairs o~ aaration colu~ns 14A~ 14b, ...
14c''' are lntercon~ect~d to allow ~clectlvc cir~ulation of tho li~uor and thc cau~tic solution. Figure 2 ~hows 35 the physicnl arrangement of the pairs of aeration columns and the circulation system for liquor and caustic .. ~. . -: : , -``` 1331~q5 - 8 - : ~
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solution, and Figure 3 shows the conceptual diRposition of the separation column~ 25 in each pair o aeration eolumns at ~h~ variou~ stages.
The liquor is introd~ced into the first stage 5 of the array 14 which ~ompri.ses the pair of aeration columns 14a. The liquor is introduce~ into the separation column 2S thereof at the inlet liquor port 31 and flo~s do~nwardly to the ~ase of the separation column :
25. ~he liquor discharged from the outlet port 33 ifi 10 circulated by a liq~or p~mp ~7 to the second stage of the array 14 which comprises the pairs of aeration columns 14b and 14b'. The stream of liquor is split equally so -~
that ~alf of the original volume is introduced through inlet port 31 into the separation colu~n 25 of thc pair 15 o aeration columns 14b and the other half is introduced throu~h the inlet port 31 i.nto the separation column 25 of the pair of aeration columns 14~'. After flowing throu~h the second stag~ the liquor is discharged ~rom the outlet ports 33 of respective separation columns 25 20 and i9 collectively circulate~ by a second stage pump 38 to the third stage of the array 14 whieh comprises the pairs of aeration columns 14c, 14c', 14c'' and 14c'''.
The recollected liquor is split equally into four streams such that a quarter of the original volume 1~ introduced 25 into the sepAraeion colu~n 25 of the pair o~ aeration columns 14c and so on up to the pair of aeration columns 14c'''. After discharge from the third stagc the liquor is combined in a single pipeline 38 and i~ transferred ~o tho final aeration stage 15 and thcnce to the columns 16 .
30 prior to eventual discharge as shown in ~igure 1 of the drawings.
Thc cau~tic ~olution i9 pumped f~om a-bulk caustic storage tank 19 via a pip~ line 39 and initially is dischar~ed into a causti~ circulation tank 20a 35 intended to supply the third stage o~ the array 14 of aeration columns, i.e. Gonverse to the supply o liquor .. . . ..... ..
- 9 - 1 ')3 1 ~q 5 w~ich is fed initiall~ to the first stage of the array 14 as described in the pre~eding paragra~h. Water from a water storage tank 23 is also pumped i~to the third stage caustic circulation tank 20a via a pipe line 2~. In a 5 closed circuit arrangement, ~he diluted caustic solution accumulated within the thi.rd stage circulation tank 2~a is circula~ed by means of a third stage caustic recirculation pump 40 from the circ~lat.ion tank 20a to each of the absorption columns 26 in the th.ird stage of 10 the array 14, i.e. the absorpti~n col~mns 26 in the pairs of aeration columns 14c, 14c', 14c'' and 14c'''. ~n each of the absorption columns 26 of t~e third stage, the caustic solution is sprayed from the top through the inlet liquor ports 34 and flows through the absorption 15 columns 26 and subsequently is di~charged through the outlet liquor ports 3~. Each of the outlet ports 36 of the absorption columns 2fi of t~e third stage are connected to a common return pipe line 41 w~ich discharges back into the third stage recirculation tank 20 20a, wherein excess caustic solution subsequently is fed via pipe line 42 to a second stage circulation tank 20b.
The accumulated caustic solution in the second stage circulation tank 20b in turn is pumped via a second stage caustic recirculation pump 43 to each of tho absorption 25 columns 26 of the second stage, i.e. the absorption columns ~6 in the pairs of aeration columns 14b and 14b'.
As in the third ~tage, the caustic solution is sprayed into the absorption columns 26, through inlet ports 34 and flows downw~rdly and i8 discharged throu~h the outlet ~r/.
30 ports 26 thereof. Subsequent~y, the discharged caustic solution iS fed to a common rcturn pipe line 44 for return to the second ~ta~e oircul4tion tank 20b, thus providin~ a closed loop circulation. The exces~ caustic ~olution contained within the second ~ta~e caustic 35 circul~tion tank 20b in turn is suppl~cd to a first~stagc caust~c circulation tank 20c via pipe line 45. Caustic :
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solution ~upplied to the first stage cir~ulation tank 20c, in tur~ is pumped via the first stage recirculation pump 46 to the absorption column ~6 of'the first stage;
i.e. the abgorption column ~6 of the pair of aeration ~-~
5 ~olumns 14a. The caustic solution, as in ~he previous stages, flows downwardly and subsequently i9 discharged through the o~tlet port 36 for return via pipe line 47 to the first sta~e circulation tank ~Oc. ~o complete the circuit, excess ~austic solution in the first stage 10 circulation tank 20c in turn is fed to a final caustic circulation tank 20d to be subsequ~ntly returned for use in the mineral recovery plant for leachin~.
It should be ~vident that the concentration of absorbed cyanide within the causti~ solution in~reases as 15 the caustic solution is cir~ulated from the third staqe ~o the ~irst stage for collection in the final circulation tank 20d. It should also be evident that each stage of the array 14 of aeration columns receives therethrou~h substantially the sa~c volume of liquor and 20 that cach pair of aeration columns 14a, 14b, ... 14c''' in each sta~ receives thcrethrough substantially the same volume of liquor and causti~ solution.
Air is drawn serially throug~ the pairs of aerator ~olumn~ 14a, 14b, ... 14c''' by fan~ 48a and 48b 25 disposed respectively at the outlet air ports 3~ of the pair ~f aeration columns 14c' and th~ pair of aeration columns 14c'''. The inlet air ports 28 of the pairs of aeration columns 14a, 14b are vented to the atmosphere so that air may be drawn from the inlet ports 28 to the 30 outlet ports 30 in ~ serial ~ashion through t~e aer~tion columns. As h~s been p~viously deqcribed, the in~crm~diate ~ir ducts 29 b~twccn ad~acent se~aration and absorption columns 25, 26 in ea~h pair o~ aeration columns are arran~ed so as to crsate risin~ air streams 3~ counter-current to the downward flow o~ liquor and causti~ solution in the aeration columns.
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An i~portant aspect of the ¢~bodiment of the invention as described herein is the circulation of liquor and air through the stages o the~array 14 of aeration columns. This is best illustrated in Figure 3 S where it can be secn that an init~al volume of liquor is passed wholly through the first sta~e comprising the pair of aeration columns 14a and is s~bsequently divided into two half vol~mes which respec~ively pass through the second stagc comprising the pairs of aeration colunns 10 14b, 14b'. The hal volumes of cyanide liq~or are subsequently divided again at the third stage ~omprisin~
the pairs of a~ration columns 14c, 140', 14c'', 14c' " so that quarter volumes o~ the original liquor volume arc passed throu~h each pair of aeration columns of the third 15 stage. These quarter volumes are then recombined into A
single supply pipe for eventual delivery to the final aeration sta~es ~s previously described. Simultaneously with the reduction in volume of the liquor, a single volume of air is passed through the various colu~n~
20 serially so that each separation and absorp~ion column 25, 26 i~ treated with the same vol~me of air.
Therefore, the air to li~uor ratio increases as the liquor passes through the pairs of aeration columns in successiv~ stages without an increase in the amount of 25 air requir~d in ~he system. As a consequence, thore Is an improvement in thc contact time for the liquor and air and a conseq~ential improvement in the ~eparation of c~anide from the liquor.
It should be appreciated that the scope of the 30 present invention is not limited to the particular embodiment h~rein descr;ibed. In particular, the invention is not limited to application to gold extraction proccsse~ and can be ufied elsewhere ~or tho separation of cyanide from a liq~id. Furthe~, the ` - . -~
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- ~ 1 331 ~95 invention is not restricted to the separation o~ cyanide from a liquid and relat~s to the separation o~ any dissolved gas from a liquid.
There exists scope ~o vary both the application 5 of the present invention and the form of the invention from the embodiment herei.n described.
In this regArd, other applications of the invention include all cyanidc containin~ waste solutions and liquors such as:
(a) mineral processing liquorsS
(b) el~ctroplating solutions;
tc) electro~inning solutions; and (d) ~annery liquors.
In addition, variations to the e~bodiment 15 herein described include:
(a) the use of all and varied flocculating and coagulating agents;
(b) the usc of any inert, particulate matorial herein before referred to a~ "sand";
2Q (c) the use of a multiplicity of any or all of steps 1-8 shown in Figure 1;
~d) the use of a multiplicity of any or all of th~ separation columns 2S;
(e) the use of A multiplicity of any or all 25 of the absorption columns 26S
(f) the use of an~ and all combinations of separation and absorption columns 25, 26 so as to effect variation in the air:liquor ratios employed;
(q) the use of a multiplicity of final 30 aerntion stages 15 shown in Figure l;
(h) the use of any subsequent water conditioning pro~cs.~ spe~ifically to regulatc dis~harge pH and compo.sition including repeatin~ the application of - .
any or all o~ the stages herein before desc~ibed5 And ~;, .. -: .: ', , :- .,, ' :
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~ i) the use of agents to materially change and/or control the temperature at which the process takes place.
In particular, whilst in the preferred 5 embodiment a strea~ of liquor flowin~ from a separation ~olumn in one stage is divided into two ~qual-volume portions for introduction into separation colllmns in the successiv~ stage, it can readily be appreciated that the invention is not so limited and the stream of liquor 10 could be divided into more than two portions which may or may not be of equal volu~e. Further, whilst in the preferred embodiment the array 14 of aeration columns is arranged in three stages, it can readily be appreciated that any suitable number of sta~es could be used.
15 Further, whilst in the preferred embodiment the air is piassed through t~e pairs of aeration col~mns serially, it can rcadily bo appreciated that any suitable air flow could be used.
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CYANIDE E'ROM ~AlLS LIQUOR
Thc present invention r~lates to a method and a system for treating by ~eration a liquid contai~ing a ... . .
component to separat~ th~e ~omponent from the liquid. In particular, the present invention relates to a method and 10 a 3ystem ~or tre~ting by aeration a liquid Gontnining - -cyanide to separate cyanid~ from the liq~id.
~t i9 known to flcrate ~ liquid to sep~rAte from e~e liquid any dissolved gases in the l~quid. For example, it is known to aerate liquid containing 15 dissolved cyanide to separate the cyanide from the liquid.
q'j One problem associated with known aeration techniques i9 that a considerable volume of air is required in proportion to the volume of liquid.
An object of the present invention is to alleviate the problem described in the preceding paragraph and to provide a more efficient and cost effective method and system for treating by aeration a liquid containing a component to separate the component from the liquid.
In a broad aspect, the present invention relates to a method of separating a component from a liquid containing the component, comprising passing the liquid downwardly through each aexation column in an array of aeration columns arranged in stages so that the liquid flowing from an outlet of one aeration column in a first stage is divided into two or more streams which are introduced into separate aeration columns in a successive second stage and passing air serially through each of the aeration columns in each stage counter-current to the liquid to entrain at least a portion of the component in - the air thereby to separate at least the portion of the component from-the liquid.
In another broad aspect, the present invention relates to a system for separating a component from a liquid containing the component, comprising a plurality of aeration columns to receive the liquid therethrough, the aeration columns arranged in a series of stages so that in use liquid which flows through one said aeration column in a first stage is subsequently divided into at least two separate streams and the streams are directed into separate aeration columns in a second stage downstream from the first stage, eàch aeration column having an inlet for spraying liquid downwardly through the column and an inlet for directing a stream of air upwardly through the column so that the liquid and the air flow in counter-current relationship and a means to direct air serially through _ . ., ~. .... .
~; . - ---' ~ . -. ..
1 33 1 ~' 9 , -2a-each aeration column in each stage in counter-current relationship to the liquid to entrain the component in the air, thereby to separate the component from the liquid.
According to the present invention there iB
provided a method of separating by aeration a component from a liquid containing the component comprising, in a first stage, passing the liquid counter-current to a stream of air to entrain a portion the component in the air thereby to separate the portion from the liquid, ~ubsequently dividing the liquid into a plurality of divided portion~3, and, in a second stage, passing each divided portion counter-current to a stream of air so as to entrain a further portion of the component in the air -thereby to separate the further portion from the liquid. -Preferably, the component comprises cyanide.
Preferably, according to the present invention there is provided a method of separating by aeration cyanide from liquid containing cyanide, comprising:
(a) adjusting the pH of the liquid to be in the acidic ~-~
range to cause the formation of free hydrogen cyanide -~
gas in the liquid;
(b) passing the liquid through an array of aeration columns arranged in stages so that the liquid flowing from one aeration column in a first stage is divided into two or more streams which are introduced into separate aeration columns in a successive second stage; and - ~--,p~ ,.
, ~, . . .
~'~3i~9~
;
(c) passin~ air t~rough the aeration columns counter-current to the liquid to entrain the free hydrogen cyanide gas, thereby to separate cyanide from the liquid.
~ccording to the present invention therc is also provided a system for separating a component from a liquid containing the component, comprifiin~:
(a) a plurality of aeration columns to : t~, receive thc liquid therethrough, the aeration columns arranged in a series of stages so that, in use, liquid which flows through one said aerati.on column in a ~irst stage is subsequently divided into at least two separate streams and the streams are directed into lS separate said aeration columns in a second stage downstream from the first st~e: and ~) means to direct air t~rou~h the aeration columns counter-current to the liquid to entrain the component in the air, thereby to separate the component from the liquld.
~` Preferably, when the system is u~ed to sep~rate cyanide from a liquid, in accordance with the invention the system oomprises a means to adjust the pH of the liquid to be in tho acidic range to cause t~e formation 25 of free hydro~en cyanide ~as in the li~uid prior to the introduction of th~ liquid into the aeration columns.
The term "column`' is understood ~erein to mean any container or the like, suoh as an open ended tube which is adapted to receive liquid therein.
The term "aeration" i~ understood herein to mean a process in which a liq~id is exposed to th~ action of air or any other ~ration gas.
The invention is now descr~bed in moro detail with reference to a specific c~bodiment thereof. The 35 description is ~ade with reference to the acco~panying drawings, in which;
,, _ . . . ~ . . . :
.~
Q ''~
1 33 1 ~9~
~igure 1 is a schematic block diagram of a tailings treatment process in its entiret~; -Pigure 2 is a detailed schematic drawing showing the particular arrangement of the aeration 5 columns and c~ustic circulation tanXs used in the proccss;
Fi~ure 3 is a block diagram showing the principal of passing air through t~e aeration columns in a serial manner without changing the volume of air 10 relative to each aeration eolumn; and -~
Fig~re 4 is a detailed schematic diagram showing th~ manner in which air passes through a single pair of separation and absorption aeration col~mns counter-current ~ith the liquor And c~ustic solution.
The specific e~bodiment concerns a system and proces~ for treating tailings from an extraction plAnt for the reco~ory of gold or other minerals.
In. one known process for extracting gold fro~
its ore, cyanide is dissolved in water and ~he resultant 20 solution is used to leach gold from d~posits of ore. In t~c leaching process, some of the cyanide remains in the tailings or the residue f~om the. plant. The purpose of the system and process dcscribed herein is to treat the tailinqs so as to r~move suf~icient of the cyanide to 25 enabl~ the tailings to be disposed of in an environmentally satis~actory condition.
The system and procefis initially comp~ises ~orming a tails liquor from the tailin~s dump which is dccanted by known meAnS 1 and pumped to a mixing chamber 30 2~`
Acid Rtored in a bulk ac1d storage tank 3 is pumpQd by ~n acidification doaing pump to the chamber for AdmixtUrc with the tails liquor so as to adjust to thc pH
of the liquor into the acid rang~ thereby to eause th~
35 formation of free hydrogen cyanide gas which is retained in the liquor.
_ From th~ mixi~g chamber 2, the liquor is pumped into a sand-floc cohtact tank 4. Coagulant, ~locc~l~nt and make-up sand from respective s~orage tanks 5, 6 and 7 are added to the sand-floc contact tank 4. The mixtur~
S is agitated and flows h~ ~ravity to a constant density tan~ 8 The underflow from the const~nt density tank 8 is pumped to a ~yclone 9. The cyclone underflow is returned to the sand-floc contact tank 4 for re-use. The 10 cyclone overflow is directed to a settling pond 10 from which liquor is drawn off and returned to t~c sand-floc contact tank 4 and the liquid is transferred to pondage.
The liquor from the constant density tank B
flows by gravity through sand filters 12 and then is 15 pumped to a column 13a. The column 13a is a preliminar~
aeration column for the separation of cyanido from the liquor. In this re~ard, th~ liquor is sprayed into the column 13a a,nd flows downwardly therethrough counter-current to a stream of air directed upwardly 20 through thc column 13a. The stream of air is drawn fr~m the constant density tank 8 and has the effect of entraining a portion of the free hydrogen cyanide gas in the liquor. The air is drawn from the top of column 13a and is directed through an absorption column 13b for 25 ab~orption of the hydrogen cyanide gas into a caustic solution.
The liquo~, with a reduced cyanide concentration, which collects at ~he bottom of the oolumn 13a is pumped to an array of aeration columns, generally 30 identified by the numerall 14, to remove a ~urther portion of the c~anide in the liquor. The aeration column~ in thu array 14 are Arranged in ~ta~e* so that the liquid flowing from onc aeration column in a fir~t stage is divided into t~o strea~s which are introduced into two 35 s~parat~ aeration columns in a successive second staqe.
~he aeration columns in the array 14 are also arranged to . - , i'~_``~.. ,' . ' `~ ~ 33 1 ~5 receive therethrough alr in counter-current flow to the flow of liquor, thereby to entrain free hydrogen cyanide gas in the air. The array 14 of aeration columns i9 described in more detail hexcinafter.
The liquor. with a substantially red~ced cyanide concentration, which passes thro~gh the final ~tage of the array 14 of aeration columns, is conveyed to a final aeration colu~n 15. Thc liquor i~ passad downwardly through the aeration co~umn 15 counter-~urrent 10 to an upward flow of air drawn from the atmosphere.
The liquor from the final aeration column 15, being clean and substantially free of cyanide, is passed through columns 16 which Contain carbon to colloct any residual gold in t~e liquor. The liguor from the columns 15 16 is suitable ~or disposal. Such disposal may ~e by direct transfer to a tailings impoundment system or via A
pH correction stage 17 where a suitable reagent such as -~ -lime or caustic soda is added to rai~e the p~ of the l~quor t~ a level ~uitable for dischar~e into the 20 environment.
The array 14 of aeration columns is now described in more detail with reference to Figures 2 and 4. The array comprises a plurality of pairs of aeration columns 14a, 14b, ... 14c''' w~ich ar~ arranged in thre~
25 stages. The first stage comprises the pair oP aeratlon col~mns 14a, the second stagc comprises the pairs of aeration columns 14b, 14b' and the t~ird ~tage comprises the pairs of aeration columns 14c, 14c', 14c'' and 14c'''-Each pair af ae~ation columns 14a, 14b 14C''' compris~s, an aeration column 25 ~or use in connection with tho sep~ration of free hydro~en cyanidc gas from liquor by means of a counter-curren~ flow o~
air, and an aeration column 26 for use in connection with 35 the absorption of hydrogen cyanide ~as ~rom the air in~o a stream o~ caustic solution.
I ~ 3 ~
-- 7 -- ~ .
.,, "", ~,, The separation column 25 and absorption column 2~ in each pair are separated ~y an intermediate air duct 29 which maintains liquor in separation column 25 and caustic solution in ~bsorption column 26 whilst al.lowing 5 air flow 27 to pass serially through bot~ columns fro~ an inlet air port 28 disposed in the separation column 2S to an outlet air port 30 disposed in the absorption ~olumn 26. In this manner air is passed serially through the columns 25, 26 in each pair.
The liquor i~ introduced in a spray through an inlet liquor port 31 disposed nuar the top of ea~h separntion ~olumn 25 and flows downwardly and is discharged through an outlet ].iquor port 33 near the ~ase of e~ch separation col~mn 25. Each separation column 2S
15 contains a bed of pao~ing material 32 s~spended theroin to promote dispersion of the downward flo~ of liquor and upward flow of air thereby to en~ance aeration of thc liquor ~nd,.as a consequence, to enhance entrainmcnt of the free hydrogen cyanide gas in the air.
: 20 Similarly, the caustic solution is introduced in a spray thro~gh a Gaustic inlet port 34 disposed ncar the top of each absorption column 26 and flows downwardly and is discharged through a ca~stic outlet port 36 disposed near the bas~ of ~ach absorption colu~n 26. In 25 addition, each absorption column 26 contains a bed of packing material 35 suspended ther~in to promote ., dispersion o the downward flow of caustic solution and upward flow of air thereby to cnhance aeration of the caustic solution and, as a consequ~nce, to enhance 30 absorption oF the hydrogen cyanide gas in the caust.io solution~
Th~ pairs o~ aaration colu~ns 14A~ 14b, ...
14c''' are lntercon~ect~d to allow ~clectlvc cir~ulation of tho li~uor and thc cau~tic solution. Figure 2 ~hows 35 the physicnl arrangement of the pairs of aeration columns and the circulation system for liquor and caustic .. ~. . -: : , -``` 1331~q5 - 8 - : ~
.
solution, and Figure 3 shows the conceptual diRposition of the separation column~ 25 in each pair o aeration eolumns at ~h~ variou~ stages.
The liquor is introd~ced into the first stage 5 of the array 14 which ~ompri.ses the pair of aeration columns 14a. The liquor is introduce~ into the separation column 2S thereof at the inlet liquor port 31 and flo~s do~nwardly to the ~ase of the separation column :
25. ~he liquor discharged from the outlet port 33 ifi 10 circulated by a liq~or p~mp ~7 to the second stage of the array 14 which comprises the pairs of aeration columns 14b and 14b'. The stream of liquor is split equally so -~
that ~alf of the original volume is introduced through inlet port 31 into the separation colu~n 25 of thc pair 15 o aeration columns 14b and the other half is introduced throu~h the inlet port 31 i.nto the separation column 25 of the pair of aeration columns 14~'. After flowing throu~h the second stag~ the liquor is discharged ~rom the outlet ports 33 of respective separation columns 25 20 and i9 collectively circulate~ by a second stage pump 38 to the third stage of the array 14 whieh comprises the pairs of aeration columns 14c, 14c', 14c'' and 14c'''.
The recollected liquor is split equally into four streams such that a quarter of the original volume 1~ introduced 25 into the sepAraeion colu~n 25 of the pair o~ aeration columns 14c and so on up to the pair of aeration columns 14c'''. After discharge from the third stagc the liquor is combined in a single pipeline 38 and i~ transferred ~o tho final aeration stage 15 and thcnce to the columns 16 .
30 prior to eventual discharge as shown in ~igure 1 of the drawings.
Thc cau~tic ~olution i9 pumped f~om a-bulk caustic storage tank 19 via a pip~ line 39 and initially is dischar~ed into a causti~ circulation tank 20a 35 intended to supply the third stage o~ the array 14 of aeration columns, i.e. Gonverse to the supply o liquor .. . . ..... ..
- 9 - 1 ')3 1 ~q 5 w~ich is fed initiall~ to the first stage of the array 14 as described in the pre~eding paragra~h. Water from a water storage tank 23 is also pumped i~to the third stage caustic circulation tank 20a via a pipe line 2~. In a 5 closed circuit arrangement, ~he diluted caustic solution accumulated within the thi.rd stage circulation tank 2~a is circula~ed by means of a third stage caustic recirculation pump 40 from the circ~lat.ion tank 20a to each of the absorption columns 26 in the th.ird stage of 10 the array 14, i.e. the absorpti~n col~mns 26 in the pairs of aeration columns 14c, 14c', 14c'' and 14c'''. ~n each of the absorption columns 26 of t~e third stage, the caustic solution is sprayed from the top through the inlet liquor ports 34 and flows through the absorption 15 columns 26 and subsequently is di~charged through the outlet liquor ports 3~. Each of the outlet ports 36 of the absorption columns 2fi of t~e third stage are connected to a common return pipe line 41 w~ich discharges back into the third stage recirculation tank 20 20a, wherein excess caustic solution subsequently is fed via pipe line 42 to a second stage circulation tank 20b.
The accumulated caustic solution in the second stage circulation tank 20b in turn is pumped via a second stage caustic recirculation pump 43 to each of tho absorption 25 columns 26 of the second stage, i.e. the absorption columns ~6 in the pairs of aeration columns 14b and 14b'.
As in the third ~tage, the caustic solution is sprayed into the absorption columns 26, through inlet ports 34 and flows downw~rdly and i8 discharged throu~h the outlet ~r/.
30 ports 26 thereof. Subsequent~y, the discharged caustic solution iS fed to a common rcturn pipe line 44 for return to the second ~ta~e oircul4tion tank 20b, thus providin~ a closed loop circulation. The exces~ caustic ~olution contained within the second ~ta~e caustic 35 circul~tion tank 20b in turn is suppl~cd to a first~stagc caust~c circulation tank 20c via pipe line 45. Caustic :
. - : . .
.~ . .. ` ` ': , . , .
'~
...
- 10 - 1 33 1 ~ 9~
solution ~upplied to the first stage cir~ulation tank 20c, in tur~ is pumped via the first stage recirculation pump 46 to the absorption column ~6 of'the first stage;
i.e. the abgorption column ~6 of the pair of aeration ~-~
5 ~olumns 14a. The caustic solution, as in ~he previous stages, flows downwardly and subsequently i9 discharged through the o~tlet port 36 for return via pipe line 47 to the first sta~e circulation tank ~Oc. ~o complete the circuit, excess ~austic solution in the first stage 10 circulation tank 20c in turn is fed to a final caustic circulation tank 20d to be subsequ~ntly returned for use in the mineral recovery plant for leachin~.
It should be ~vident that the concentration of absorbed cyanide within the causti~ solution in~reases as 15 the caustic solution is cir~ulated from the third staqe ~o the ~irst stage for collection in the final circulation tank 20d. It should also be evident that each stage of the array 14 of aeration columns receives therethrou~h substantially the sa~c volume of liquor and 20 that cach pair of aeration columns 14a, 14b, ... 14c''' in each sta~ receives thcrethrough substantially the same volume of liquor and causti~ solution.
Air is drawn serially throug~ the pairs of aerator ~olumn~ 14a, 14b, ... 14c''' by fan~ 48a and 48b 25 disposed respectively at the outlet air ports 3~ of the pair ~f aeration columns 14c' and th~ pair of aeration columns 14c'''. The inlet air ports 28 of the pairs of aeration columns 14a, 14b are vented to the atmosphere so that air may be drawn from the inlet ports 28 to the 30 outlet ports 30 in ~ serial ~ashion through t~e aer~tion columns. As h~s been p~viously deqcribed, the in~crm~diate ~ir ducts 29 b~twccn ad~acent se~aration and absorption columns 25, 26 in ea~h pair o~ aeration columns are arran~ed so as to crsate risin~ air streams 3~ counter-current to the downward flow o~ liquor and causti~ solution in the aeration columns.
~_ . ,,,, " - ~ :
'`. ,.`, ' '' :'`
;~'i';~ ` ' ' ' ' ~ ,. :
-- 11 -- 1 s 3 1 ~ ~ ~
An i~portant aspect of the ¢~bodiment of the invention as described herein is the circulation of liquor and air through the stages o the~array 14 of aeration columns. This is best illustrated in Figure 3 S where it can be secn that an init~al volume of liquor is passed wholly through the first sta~e comprising the pair of aeration columns 14a and is s~bsequently divided into two half vol~mes which respec~ively pass through the second stagc comprising the pairs of aeration colunns 10 14b, 14b'. The hal volumes of cyanide liq~or are subsequently divided again at the third stage ~omprisin~
the pairs of a~ration columns 14c, 140', 14c'', 14c' " so that quarter volumes o~ the original liquor volume arc passed throu~h each pair of aeration columns of the third 15 stage. These quarter volumes are then recombined into A
single supply pipe for eventual delivery to the final aeration sta~es ~s previously described. Simultaneously with the reduction in volume of the liquor, a single volume of air is passed through the various colu~n~
20 serially so that each separation and absorp~ion column 25, 26 i~ treated with the same vol~me of air.
Therefore, the air to li~uor ratio increases as the liquor passes through the pairs of aeration columns in successiv~ stages without an increase in the amount of 25 air requir~d in ~he system. As a consequence, thore Is an improvement in thc contact time for the liquor and air and a conseq~ential improvement in the ~eparation of c~anide from the liquor.
It should be appreciated that the scope of the 30 present invention is not limited to the particular embodiment h~rein descr;ibed. In particular, the invention is not limited to application to gold extraction proccsse~ and can be ufied elsewhere ~or tho separation of cyanide from a liq~id. Furthe~, the ` - . -~
. :`, :.`
. . ., '~
:: .. -.' .. ~' .: ' :' ,.
- ~ 1 331 ~95 invention is not restricted to the separation o~ cyanide from a liquid and relat~s to the separation o~ any dissolved gas from a liquid.
There exists scope ~o vary both the application 5 of the present invention and the form of the invention from the embodiment herei.n described.
In this regArd, other applications of the invention include all cyanidc containin~ waste solutions and liquors such as:
(a) mineral processing liquorsS
(b) el~ctroplating solutions;
tc) electro~inning solutions; and (d) ~annery liquors.
In addition, variations to the e~bodiment 15 herein described include:
(a) the use of all and varied flocculating and coagulating agents;
(b) the usc of any inert, particulate matorial herein before referred to a~ "sand";
2Q (c) the use of a multiplicity of any or all of steps 1-8 shown in Figure 1;
~d) the use of a multiplicity of any or all of th~ separation columns 2S;
(e) the use of A multiplicity of any or all 25 of the absorption columns 26S
(f) the use of an~ and all combinations of separation and absorption columns 25, 26 so as to effect variation in the air:liquor ratios employed;
(q) the use of a multiplicity of final 30 aerntion stages 15 shown in Figure l;
(h) the use of any subsequent water conditioning pro~cs.~ spe~ifically to regulatc dis~harge pH and compo.sition including repeatin~ the application of - .
any or all o~ the stages herein before desc~ibed5 And ~;, .. -: .: ', , :- .,, ' :
r .
~r : ;` ` ;
Ø : . :
. .
- 13 - l 33 1 ~9~
~ i) the use of agents to materially change and/or control the temperature at which the process takes place.
In particular, whilst in the preferred 5 embodiment a strea~ of liquor flowin~ from a separation ~olumn in one stage is divided into two ~qual-volume portions for introduction into separation colllmns in the successiv~ stage, it can readily be appreciated that the invention is not so limited and the stream of liquor 10 could be divided into more than two portions which may or may not be of equal volu~e. Further, whilst in the preferred embodiment the array 14 of aeration columns is arranged in three stages, it can readily be appreciated that any suitable number of sta~es could be used.
15 Further, whilst in the preferred embodiment the air is piassed through t~e pairs of aeration col~mns serially, it can rcadily bo appreciated that any suitable air flow could be used.
~;.
:, :
'.! ` ~ ~ ` . ~ ` i .
~i . ` . ` ` . ' ' ` , .
"i ` ::` ` ` :` ' ' ' :
~;' `' ~
. ~ ~ ` ' . ' `
Claims (11)
1. A method of separating a component from a liquid containing the component, comprising:
(a) passing the liquid downwardly through each aeration column in an array of aeration columns arranged in stages so that the liquid flowing from an outlet of one aeration column in a first stage is divided into two or more streams which are introduced into separate aeration columns in a successive second stage; and (b) passing air serially through each of the aeration columns in each stage counter-current to the liquid to entrain at least a portion of the component in the air thereby to separate at least the portion of the component from the liquid.
(a) passing the liquid downwardly through each aeration column in an array of aeration columns arranged in stages so that the liquid flowing from an outlet of one aeration column in a first stage is divided into two or more streams which are introduced into separate aeration columns in a successive second stage; and (b) passing air serially through each of the aeration columns in each stage counter-current to the liquid to entrain at least a portion of the component in the air thereby to separate at least the portion of the component from the liquid.
2. The method defined in claim 1, wherein the liquid flowing from the outlet of an aeration column in the first stage is divided into two equal-volume streams.
3. The method defined in claim 1, wherein the component comprises cyanide, and the method comprises adjusting the pH of the liquid to be in the acidic range to cause the formation of free hydrogen cyanide in the liquid before passing the liquid downwardly through each aeration column in accordance with step (a).
4. The method defined in claim 2, wherein the component comprises cyanide, and the method comprises adjusting the pH of the liquid to be in the acidic range to cause the formation of free hydrogen cyanide in the liquid before passing the liquid downwardly through each aeration column in accordance with step (a).
5. The method defined in claim 3, comprising, extracting free hydrogen cyanide gas from the air by contacting air after it flows from each aeration column with a solution capable of absorbing free hydrogen cyanide gas.
6. The method defined in claim 4, comprising, extracting free hydrogen cyanide gas from the air by contacting air after it flows from each aeration column with a solution capable of absorbing free hydrogen cyanide gas.
7. The method defined in claim 5 or 6, comprising, passing air flowing from each aeration column through an absorption column and passing the absorption solution counter-current to the air.
8. A system for separating a component from a liquid containing the component, comprising:
(a) a plurality of aeration columns to receive the liquid therethrough, the aeration columns arranged in a series of stages so that in use liquid which flows through one said aeration column in a first stage is subsequently divided into at least two separate streams and the streams are directed into separate aeration columns in a second stage downstream from the first stage, each aeration column having an inlet for spraying liquid downwardly through the column and an inlet for directing a stream of air upwardly through the column so that the liquid and the air flow in counter-current relationship; and (b) a means to direct air serially through each aeration column in each stage in counter-current relationship to the liquid to entrain the component in the air, thereby to separate the component from the liquid.
(a) a plurality of aeration columns to receive the liquid therethrough, the aeration columns arranged in a series of stages so that in use liquid which flows through one said aeration column in a first stage is subsequently divided into at least two separate streams and the streams are directed into separate aeration columns in a second stage downstream from the first stage, each aeration column having an inlet for spraying liquid downwardly through the column and an inlet for directing a stream of air upwardly through the column so that the liquid and the air flow in counter-current relationship; and (b) a means to direct air serially through each aeration column in each stage in counter-current relationship to the liquid to entrain the component in the air, thereby to separate the component from the liquid.
9. The system defined in claim 8, wherein the component comprises cyanide, and the system further comprises a means to adjust the pH of the liquid to be in the acidic range to cause the formation of free hydrogen cyanide gas in the liquid.
10. The system defined in claim 9, further comprises a plurality of absorption columns for receiving therethrough air from the aeration columns and for receiving therethrough a counter-current flow of a solution capable of absorbing the hydrogen cyanide gas entrained in the air.
11. The system defined in claim 10, wherein the aeration and absorption columns are arranged in pairs with each pair interconnected so that in use air flowing from the aeration column in one pair flows into the absorption column in the same pair.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPI157087 | 1987-04-23 | ||
| AUPI1570 | 1987-04-23 | ||
| AUPI3780 | 1987-08-17 | ||
| AUPI378087 | 1987-08-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1331895C true CA1331895C (en) | 1994-09-06 |
Family
ID=25643268
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000564951A Expired - Fee Related CA1331895C (en) | 1987-04-23 | 1988-04-22 | System and method for the extraction of cyanide from tails liquor |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0355109A4 (en) |
| CA (1) | CA1331895C (en) |
| MY (1) | MY103266A (en) |
| NZ (1) | NZ224369A (en) |
| WO (1) | WO1988008408A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5078977A (en) * | 1988-10-21 | 1992-01-07 | Cyprus Minerals Company | Cyanide recovery process |
| US5254153A (en) * | 1988-10-21 | 1993-10-19 | Cyprus Minerals Company | Cyanide recycling process |
| US4994243A (en) * | 1988-10-21 | 1991-02-19 | Cyprus Minerals Company | Cyanide regeneration process |
| DE19600774A1 (en) * | 1996-01-11 | 1997-07-17 | Biotecon Ges Fuer Biotechnologische Entwicklung & Consulting Mbh | Removal of cyanide from process water |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1387289A (en) * | 1918-03-21 | 1921-08-09 | Merrill Co | Cyaniding process |
| DE409259C (en) * | 1924-05-31 | 1925-02-03 | Atlas Werke Ag | Process for cleaning and degassing raw water by boiling the water |
| DE2156186A1 (en) * | 1971-11-12 | 1973-05-17 | Babcock & Wilcox Ag | Feedwater degassing tank - with closely spaced nozzles to achieve contacting spray cones |
| GB1577214A (en) * | 1976-07-14 | 1980-10-22 | Brewing Patents Ltd | Production of deoxygenated water for use in brewing |
-
1988
- 1988-04-22 EP EP19880903747 patent/EP0355109A4/en not_active Withdrawn
- 1988-04-22 CA CA000564951A patent/CA1331895C/en not_active Expired - Fee Related
- 1988-04-22 MY MYPI88000414A patent/MY103266A/en unknown
- 1988-04-22 WO PCT/AU1988/000119 patent/WO1988008408A1/en not_active Application Discontinuation
- 1988-04-26 NZ NZ224369A patent/NZ224369A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| NZ224369A (en) | 1990-05-28 |
| WO1988008408A1 (en) | 1988-11-03 |
| MY103266A (en) | 1993-05-29 |
| EP0355109A4 (en) | 1990-03-12 |
| EP0355109A1 (en) | 1990-02-28 |
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