CN1699174A - Method for regenerating sodium cyanide from solutions containing cyanogen and thiocyanate - Google Patents
Method for regenerating sodium cyanide from solutions containing cyanogen and thiocyanate Download PDFInfo
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- CN1699174A CN1699174A CN 200510016777 CN200510016777A CN1699174A CN 1699174 A CN1699174 A CN 1699174A CN 200510016777 CN200510016777 CN 200510016777 CN 200510016777 A CN200510016777 A CN 200510016777A CN 1699174 A CN1699174 A CN 1699174A
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Abstract
The invention relates to a method for regenerating sodium cyanide from solutions containing cyanogen and thiocyanate, which comprises the steps of reclaiming noble metal, pre-processing barren liquor, reclaiming cyanides in the barren liquor, regenerating sodium cyanide from sulfocyanate, arsenic disposing and returning filter liquor after advanced treatment of cyanides. The precious-metal recovery rate can reach 95%, the recovery ratio of cyanides in the barren liquor can reach over 99.5%.
Description
Technical Field
The invention relates to a method for regenerating sodium cyanide, in particular to a method for regenerating sodium cyanidefrom a cyanide-containing and thiocyanate-containing solution.
Background
At present, the traditional equipment of the mature acidification recovery method mainly comprises an acidification generating tower, a sodium cyanide absorption tower, a fan, a barren solution storage tank, a barren solution pump, a sedimentation tank, an acid mixer, a sulfuric acid head tank, an alkali liquor circulating pump, a submerged pump or a metering pump, a barren solution heating device and the like; the technical level of the domestic and overseas acidification recovery method is basically the same, and the process is roughly divided into five parts, namely devices such as preheating of waste water, acidification, stripping (volatilization) of HCN, absorption of HCN gas, separation of precipitates in the waste water and the like;
the separation process of the precipitate can also be placed after acidification and before HCN stripping, the precipitate is prevented from blocking filler of an HCN generation tower, but the precipitate contains high-concentration cyanide acid solution, so that the precipitate is dangerous to poison and the recovery rate of cyanide is reduced in the drying process of the precipitate, and the precipitate separation equipment needs to be antiseptic and closed, so that the investment of the equipment is increased.
At present, there are two main methods for regenerating cyanide from thiocyanate:
the first is the process of regenerating cyanide from thiocyanate with ozone process, and its main principle is that the mixed liquid of ozone and air reacts with thiocyanate to produce CN under the condition of pH lower than 6-But ozone does not react with CN under acidic conditions-Reacting to achieve the aim of regenerating cyanide; the process is suitablefor use with low concentrations of thiocyanate (SCN)-Less than 500mg/L) solution, and is not suitable for regeneration when the concentration of thiocyanate in the solution is high, the first reason is that the power consumption required by ozone generation is large (15-20 kw is required for generating 1kg of hydrogen peroxide), and the second reason is that no mature technology of an ultra-large hydrogen peroxide generator exists in China at present.
Secondly, the cyanide is regenerated from the thiocyanate solution of the cyanidation process by an electrochemical method, and the main principle of the method is that the thiocyanate is subjected to cathodic electrochemical reaction in a special double-electrode electrolytic cellShould generate CN-The purpose of cyanide regeneration is achieved, but the method must be carried out under an acid medium to have the possibility of regenerating cyanide, and only a part of cyanide can be recovered, and the reason is mainly CN-Also electrochemically reacted at the cathode of the electrolytic cell to produce CNO-、NH3And N2At present, the method is not applied to the industry, and needs to be improved.
Disclosure of Invention
The invention aims to provide a method for regenerating sodium cyanide from a cyanide-containing and thiocyanate-containing solution, in particular to a method for recovering cyanide in the cyanide-containing solution by using an acidification-jet aeration generation-absorption method; the technology for effectively controlling the oxidation of thiocyanate to regenerate cyanide by the oxidation of thiocyanate and the method for regenerating subsequently used free cyanide by a jet aeration generation-absorption method after oxidizing thiocyanate with hydrogen peroxide under acidic conditions solve the problems that the existing cyanide regeneration process is not suitable for regeneration when the concentration of thiocyanate in a solution is high, the cyanide regeneration is possible only by carrying out under an acidic medium, only a part of cyanide can be recovered and the like.
The invention comprises the following steps:
step 1 is the recovery of precious metals:
the lean solution generally contains precious metals such as gold, silver and the like with certain recovery value, and because the precious metals in the lean solution are low in grade and the occupied area of a workshop is saved, the precious metal recovery process finally adopts fluidized bed activated carbon adsorption, and an adsorption column adopts a three-stage series adsorption device; during normal production, the barren solution is metered into a series adsorption column from a barren solution storage tank and a barren solution pump of a cyanide plant, and in the process, most of precious metals in the barren solution are adsorbed by coconut shell activated carbon in a fluidized state and are recovered; ion exchange dynamic adsorption is adopted in the ore pulp.
Step 2 is pretreatment:
because the gold production process is different from other conventional cyanidation plants, for example, the gold concentrate biological oxidation-cyanidation process mainly shows that: the copper content is low, the cyanide and thiocyanate content is high (3000-6000mg/l), the lean solution contains a large amount of organic substances, if the lean solution enters a treatment system, the equipment cannot operate, meanwhile, certain difficulty is brought to secondary treatment, and the lean solution is finally determined to be pretreated;
the barren solution with the recovered noble metal is fed into two parallel acidification-aeration generation reaction kettles from the adsorption column of the third polar fluidized bed by an original barren solution pump, and after the barren solution enters the acidification-aeration generation reaction kettles, pretreatment is firstly carried out, and the main method of the pretreatment is that the barren solution is heated, so that long carbon chains of the cyclohexene oxide are broken to achieve the purpose of pretreatment; the barren liquor heating method comprises two modes, namely electrical heating and heating in a gas-liquid jet aeration mode by utilizing the residual high-temperature (100 ℃ in summer and 80 ℃ in winter) air volume of a main fan of the biological oxidation plant until the temperature is raised to 60 ℃, and stopping the electrical heating.
Step 3 is to recover cyanide:
generally, cyanide with higher recovery value is recovered from high-concentration cyanide-containing wastewater, and the cyanide is recovered by adopting an acidification-jet aeration generation-absorption method; adding sulfuric acid into cyanide-containing wastewater, and quickly converting cyanide in the wastewater into HCN under the condition that the pH value is less than 2; because the vapor pressure of HCN is high, when gas is filled into the wastewater, HCN escapes from a liquid phase into a gas phase and is taken away by gas flow, and the gas carrying HCN contacts NaOH in the absorption liquid and reacts to generate NaCN which is used for leaching again;
after the barren solution is pretreated, a cyanide recovery procedure is carried out in an original reaction kettle, concentrated sulfuric acid is fed into an acidification-aeration reaction kettle after being measured by a high potential difference from a sulfuric acid head tank, the barren solution is acidified, the concentrated sulfuric acid in the sulfuric acid head tank comes from a sulfuric acid low level tank of a biological oxidationplant, the barren solution in an acidification logistics part is used for generating the hydrogen cyanide by an air-carrying water jet aerator, the generated hydrogen cyanide is brought into two absorption towers which are connected in series by wind pressure which is not from the biological oxidation plant, absorption liquid of the absorption towers comes from an alkali liquor circulating tank, absorption liquid of the alkali liquor circulating tank is measured by an acid-resistant pump and then fed into the two absorption towers, the absorption liquid of the alkali liquor circulating tank comes from an alkali liquor preparation tank, the hydrogen cyanide is contacted with the absorption liquid in a countercurrent mode in the absorption towers to neutralize to generate a sodium cyanide product, and the hydrogen cyanide-free gas after two-stage absorption is discharged from the top of the; the reaction principle is as follows:
step 4 is the regeneration of sodium cyanide from thiocyanate:
after cyanide is recovered, a working procedure of regenerating sodium cyanide from thiocyanate is carried out in an original acidification-aeration reaction kettle, hydrogen peroxide is metered from a hydrogen peroxide high-level tank by high level difference and then fed into an acidification-aeration generation kettle to oxidize the thiocyanate, the hydrogen peroxide in the hydrogen peroxide high-level tank comes from a hydrogen peroxide low-level tank in a comprehensive treatment workshop of the barren solution, the oxidized barren solution is provided with a water jet aerator by air to generate hydrocyanic acid, the generated hydrocyanic acid is brought into two absorption towers connected in series by the air pressure from a biological oxidation plant, the hydrocyanic acid is in countercurrent contact with the absorption solution in the absorption towers to be neutralized to generate a sodium cyanide product, and the non-hydrogen cyanide gas after two-stage absorption is discharged from the top of a second absorption tower aloft;
the first chemical principle for the regeneration of cyanide from thiocyanate is to use a new technology of chemical oxidation, the advanced oxidation process, in which H is used2O2Plays an important role, H2O2Under alkaline conditions, the catalyst reacts preferentially with cyanide and has a high reaction speed, but has a low reaction speed with thiocyanate; the second chemical principle for the regeneration of cyanide from thiocyanate is H2O2Preferentially reacts with thiocyanate under acidic medium and warming conditions to form HCN, and the HCN formed is stable under acidic conditions due to protonation and is therefore not converted by H2O2Further reacting to regenerate cyanide. The reaction principle is as follows:
the reaction formula of hydrogen peroxide and thiocyanate under acidic conditions is as follows:
the reaction of hydrogen peroxide with cyanide under alkaline conditions is represented by the formula:
step 5 is arsenic treatment:
after the barren solution passes through the working procedure of regenerating sodium cyanide from thiocyanate, the arsenic treatment is carried out in an original reaction kettle, the arsenic treatment adopts a lime milk neutralization method, and lime milk is fed into an acidification-aeration generation reaction kettle after being metered by a high head from a lime milk high-level tank; arsenic is precipitated as ferric arsenate after neutralization; after the barren solution is subjected to an advanced treatment process, arsenic can reach the standard. The reaction principle is as follows:
step 6 is cyanide advanced treatment
After arsenic treatment, the barren solution is subjected to a barren solution advanced treatment process in an original reaction kettle, hydrogen peroxide is metered by a high head from a hydrogen peroxide head tank and then is fed into an acidification-aeration generation reaction kettle, and a small amount of residual cyanide is oxidized; the hydrogen peroxide in the hydrogen peroxide head tank comes from a hydrogen peroxide low tank of a barren solution comprehensive treatment workshop; after the barren solution is subjected to the advanced treatment process, cyanide can reach the standard, and the filtrate is returned for utilization after the barren solution is subjected to solid-liquid separation. The reaction principle is as follows:
the invention has the advantages that: since the regeneration of cyanide appears to be more attractive than direct thiocyanate decomposition, the ability to successfully regenerate cyanide from cyanide-containing, thiocyanate-containing solutions is of great value to the industry; less oxidant is required for cyanide regeneration and total cyanide consumption is also reduced; when the method is used for treating the solution containing cyanogen and thiocyanate, the recovery rate of noble metal can reach more than 95%, the recovery rate of cyanide in the barren solution can reach more than 99.5%, the regeneration rate of sodium cyanide regenerated from the thiocyanate can reach more than 85%, the total recovery rate of the cyanide is more than 94%, arsenic after treatment can reach the standard emission, and the total cyanide can reach the standard emission after advanced treatment.
Description of the drawings:
FIG. 1 is a schematic flow chart of the method of the present invention.
The specific implementation mode is as follows:
example 1:
as shown in fig. 1, this embodiment is performed in the following sequence of steps: in the cyanidation plant which uses difficultly treated concentrate as cyaniding nuclear material in the process of biological oxidation-cyanidation, because the gold and silver in the concentrate have high grade and the content of associated minerals is relatively high, the consumption of sodium cyanide is also high in the cyanidation process. The composition of the lean solution is shown in table 1:
composition of barren solution Table 1
| Composition of | CNT | CN- | Cu | Pb | Zn |
| Concentration mg/l | 5360.12 | 4423.4 | 31.67 | 0.23 | 630 |
| Composition of | Fe | SCN- | As | Au | Organic matter |
| Concentration mg/l | 11.10 | 6366.08 | 6.00 | 0.10 | 6288 |
Acidification of cyanide, which occurs and oxidation of thiocyanate, which occurs optimally when the pH is 2; when the pH value is 2, the reaction between hydrogen peroxide and thiocyanate is rapid and thorough; hydrogen peroxide reacts more slowly with cyanide at pH 2 when cyanide is available; the temperature has certain influence on the reaction of hydrogen peroxide and thiocyanate, is generally economical at about 35 ℃ and is beneficial to adding and receiving cyanide; although hydrogen peroxide and thiocyanate react slowly at low pH, the high cyanide concentrations avoid destroying cyanide and affecting recovery efficiency, so that control of the reaction kinetics is a key factor in the success of the overall process.
Step 1 is to recover precious metals:
(1) carbon is filled in the adsorption column: filling activated carbon into the series adsorption column, wherein the activated carbon is6-16 mesh coconut shell carbon, the activated carbon is cleaned in a carbon washing tank and subjected to angle grinding before being filled, particles are filled into the adsorption column after carbon powder is sieved, and the filling of the carbon is stopped when a carbon layer reaches a position 200mm below a liquid outlet of the adsorption column;
(2) flow rate of lean solution: after the adsorption column is loaded with carbon, starting a barren solution pump to adjust barren solution flow to 8-10m3Feeding the barren solution into two parallel acidification-aeration generation reaction kettles through three adsorption columns connected in series by virtue of original barren solution pumps;
(3) two acidification-injecting barren solution into the aeration reaction kettle: the two reaction kettles are both provided with liquid level display and liquid level alarm devices, and if the lean solution amount of each reaction kettle reaches 4m3The barren pump is stopped.
Step 2 is barren liquor pretreatment:
(1) heating the barren solution: the composition of the barren solution is obviously different from the composition of the prior barren solution in that the defoaming agent added in the cyanidation procedure has great influence on the acidification recovery method, and the results of small-scale tests show that a great deal of white flocculent precipitate is generated after the barren solution is added with sulfuric acid, the precipitate has great viscosity and density close to that of water, is difficult to separate by a physical method and needs to be separated by a chemical method; the lean solution pretreatment adopts a heating method, when the temperature reaches 60 ℃, the antifoaming agent contained in the lean solution, namely long carbon chains of the cyclohexene oxide are broken to achieve the purpose of pretreatment, the lean solution heating method has the following two modes, firstly, the lean solution is electrically heated, secondly, the air quantity of the residual high temperature (100 ℃ in summer and 80 ℃ in winter) of a main fan of a biological oxidation plant is utilized, the electric heating is stopped when the temperature is raised to 60 ℃, and the pretreatment is generally carried out for about 0.5 to 1 hour;
(2) the gas-liquid ratio is adjusted to be 200: 1 when the gas-liquid ratio (volume ratio) and the gas-liquid jet aeration mode are heated.
Step 3 is to recover cyanide in the barren solution:
(1) concentration of the absorption liquid: HCN is weak acid, so that the absorption liquid must keep a certain alkalinity to ensure that NsCN is not hydrolyzed; as the absorption liquid is added in batch and recycled, practice shows that when the residual amount of NaOH in the absorption liquid is reduced to below 1%, the absorption rate of HCN begins to be reduced, and the residual concentration of HCN in carrier gas is increased, so that the concentration of residual cyanide in the treated wastewater is increased; theoretically, the pH value of the absorption liquid should be more than 10; in industrial production, when the concentration of NaOH in absorption liquid is reduced to 1-2%, the absorption liquid is stopped to be recycled and is conveyed to a cyanidation working section; preparing an absorption liquid in an alkali liquor preparation tank, firstly injecting water into the alkali liquor preparation tank, stirring when the water level reaches 500m, then adding 100kg of sodium hydroxide into the alkali liquor preparation tank, wherein the concentration of the sodium hydroxide in the absorption liquid is 20%, covering a cover, stirring for 30 minutes, injecting the prepared absorption liquid into a 1 st alkali liquor circulation tank, and repeatedly injecting the prepared absorption liquid into a 2 nd alkali liquor circulation tank;
(2) filling materials in the absorption tower: opening upper and lower inlet holes of the two absorption towers, installing a filler supporting plate, installing two layers of phi 50 fillers, covering a lower inlet hole of the absorption tower, screwing screws, pouring phi 25 fillers into the absorption tower from the upper inlet hole of the absorption tower, enabling the height of a filler layer to reach the bottom of the upper inlet hole of the absorption tower, and covering the upper inlet hole of the absorption tower;
(3) adjusting the spraying density of the absorption tower: the absorption liquid supplied from the upper section is pumped into the absorption tower in the alkali liquor circulating tank by the alkali liquor circulating pump, and then flows back from top to bottom through the packing layer of the absorption towerThe flow of the circulating absorption liquid to the alkali liquor circulating tank is adjusted to the spray density of the absorption tower, and the amount of the waste water passing through the empty tower unit cross section of the absorption tower in unit time is called the spray density, and the unit of the waste water is m3/(m2H); the parameters of the method are determined by various factors, such as the type of tower packing, the filling form, the height of the packing layer, the linear velocity of carrier gas flow, the distribution condition of liquid when entering the tower, namely the dispersion degree and the like; the rule is that the absorption rate of HCN is highest when the spraying density reaches a certain value. The spray density is generally 12;
(4) acidification-aeration onset temperature: the vapor pressure of a substance is a function of temperature. If the temperature is low, its vapor pressure is also low, when the temperature reaches the boiling point of the substance, its vapor pressure is called saturated vapor pressure; when the stripping temperature is increased, HCN is easier to escape from the liquid phase into the gas phase due to the increase of the vapor pressure of the HCN; another benefit of increasing the temperature is that the viscosity of the wastewater is reduced, increasing the rate of diffusion of HCN through the liquid film to the gas; generally, water is heated to 35-40 ℃ and then acidified and blown off. The stripping temperature is not in direct proportion to the removal rate of cyanide laboratory substances, the increase range of the removal rate of cyanide becomes smaller along with the increase of the stripping temperature, and the excessive increase of the stripping humidity is not reasonable economically; acidifying the barren solution, namely, when the aeration is carried out, the optimal temperature is 35 ℃, if the barren solution does not contain an antifoaming agent (organic matters such as epoxy hexane and the like), the barren solution is heated to 35 ℃, if the barren solution contains the antifoaming agent, the barren solution is pretreated in the step 2, and the barren solution is heated to 60 ℃;
(5) pH of the lean solution: concentrated sulfuric acid is fed into the acidification-aeration reaction kettle after being measured by a head from a sulfuric acid head tank to acidify the barren solution, and the addition of the concentrated sulfuric acid is 8kg/m3Adjusting the pH value to 2; according to the reaction mechanism of the acidification recovery method, different complexes have different dissociation initial pH values and different pH values when the complexes reach equilibrium due to different stability constants and different products generated during acidification and dissociation; according to our experiments with certain waste waters,Zn(CN)4 2-has an initial dissociation pH of about 4.5Cu (CN)2 -Is 2.5, and Fe (CN)6 4-Does not dissociate even ifthe pH value is less than 1 at normal temperature; in order to recover cyanide thoroughly in production, the acid content of the treated wastewater is generally controlled to be about 0.2 percent;
(6) gas-liquid ratio: the volume ratio of gas to liquid in the reaction kettle in unit time is called as gas-liquid ratio; determining the dynamic characteristic of HCN diffusing from a liquid phase to a gas phase by the gas-liquid ratio of the generation reaction kettle; the larger the gas-liquid ratio is, the lower the HCN concentration in the gas is, and the easier HCN of the liquid phase escapes; the diffusion of HCN is controlled by liquid membrane resistance, if the gas-liquid ratio is increased, the liquid membrane resistance is reduced, the diffusion speed is accelerated, but the overlarge gas-liquid ratio can cause flooding and increase the gas resistance of the tower, and the power consumption is increased, so that the economic unreasonable effect is achieved; the gas-liquid ratio is 200, and the step of recovering cyanide in the barren solution is carried out for 3 hours;
step 4 is the regeneration of sodium from thiocyanate:
(1) concentration of the absorption liquid: the concentration of sodium hydroxide in the absorption liquid is 20%, which is specifically the same as the concentration in the step (1) in the step 3;
(2) filling materials in the absorption tower: then using the same packing of the absorption column as in (2) above in step 3;
(3) spray density of the absorption tower: spray density of absorption tower is 12m3/(m2H), specifically the same as (3) in step 3 above;
(4) oxidation-aeration generation temperature: acidification of the barren solution, namely, when aeration occurs, the optimal temperature is 35 ℃, if the barren solution does not containan antifoaming agent (organic matters such as epoxy hexane and the like), the barren solution is only heated to 35 ℃, if the barren solution contains the antifoaming agent, the barren solution is pretreated in the step 2, and the temperature of the barren solution is heated to 60 ℃, which is specifically the same as the step (4) in the step 3;
(5) pH of the lean solution: multiple experiments prove that the protonation of HCN is strongest when the pH value is 2, and the HCN is not easy to react with hydrogen peroxide to achieve the purpose of recycling, and is specifically the same as the step (5) in the step 3;
(6) gas-liquid ratio: the gas-liquid ratio was 200, specifically the same as in (6) of the above step 3;
(7) hydrogen peroxide concentration and addition: after cyanide is recovered from the barren solution, the working procedure of regenerating sodium cyanide from thiocyanate is carried out in an original acidification-aeration reaction kettle, hydrogen peroxide is metered from a hydrogen peroxide head tank by head and then fed into the acidification-aeration reaction kettle, and the concentration of the hydrogen peroxide is 30 percent at the moment, and the addition is 28kg/m3Oxidizing thiocyanate, wherein hydrogen peroxide in a hydrogen peroxide elevated tank comes from a hydrogen peroxide low tank in a barren solution comprehensive treatment workshop, the oxidized barren solution is provided with a water jet aerator by air to generate hydrocyanic acid, the generated hydrocyanic acid is brought into two absorption towers connected in series by air from a biological oxidation plant, and the hydrocyanic acid is absorbed in the absorption towersThe collected liquid is in countercurrent contact and neutralization to produce a sodium cyanide product, and the non-hydrogen cyanide gas after the two-stage absorption is discharged from the top of the second absorption towerat high altitude; the procedure of regenerating cyanide from thiocyanate is carried out for 3 hours, and then hydrogen peroxide is stopped to be added;
step 5 is arsenic treatment:
(1) stop HCN absorption unit: after the barren solution passes through the working procedure of regenerating sodium cyanide from thiocyanate, the working procedure of treating arsenic is carried out in an original reaction kettle, and at the moment, an HCN absorption device and an absorption solution (alkali liquor) circulating pump are stopped;
(2) and (3) barren liquor neutralization: the arsenic treatment adopts a lime milk neutralization method, and lime milk is metered by a high level difference from a lime milk high-level tank and then fed into an acidification-aeration generation reaction kettle; precipitating the neutralized arsenic in the form of ferric arsenate, wherein the pH value is 9.5-10, and performing arsenic treatment for 0.5 hour;
step 6 is cyanide advanced treatment:
(1) concentration of hydrogen peroxide: after arsenic treatment, the barren solution is subjected to barren solution advanced treatment in an original reaction kettle, hydrogen peroxide is metered by a high head from a hydrogen peroxide head tank and then fed into an acidification-aeration generation reaction kettle, and a small amount of residual cyanide is oxidized, wherein the concentration of the hydrogen peroxide is 0.2kg/m3The advanced treatment process is carried out for 0.5 hour;
(2) and (3) returning the filtrate after solid-liquid separation for utilization: after the barren solution is deeply treated, the barren solution is filtered and returned to the cyaniding process after being precipitated in a precipitation tank.
After the treatment by the process, in step 1, the recovery rate of precious metals such as gold and silver reaches 95.05%, the recovery rate of cyanide in the barren solution in step 3 is 97.83%, the regeneration rate of sodium cyanide regenerated from thiocyanate in step 4 is 85.27%, the total recovery rate of cyanide is 92.54%, the arsenic concentration after arsenic neutralization treatment in step 5 is 0.13mg/l and is lower than the emission standard of industrial erhu by 0.5mg/l, the total cyanide after advanced treatment in step 6 is 0.36 and is lower than the emission standard of industrial secondary grade by 0.5mg/l, and the total treatment time is 8 hours.
Example 2:
example 1 was repeated with the same procedure as described above, except that step 3 and step 4 were performed simultaneously, and the technical parameters were the same as in step 3 and step 4 of example 1; the operation procedure is that concentrated sulfuric acid is added to adjust the pH value to 2, and then the hydrogen peroxide concentration is added in time28kg/m3Then acidification, oxidation, aeration generation and absorption are carried out for 6 hours.
Example 2 after the treatment by the above method, the recovery rate of gold, silver and other noble metals in step 1 reached 95.02%, the total recovery rate of cyanide in the barren solution and sodium cyanide regenerated from thiocyanate in steps 3 and 4 was 81.51%, the arsenic concentration after neutralization treatment of arsenic in step 5 was 0.16mg/l, which is lower than the industrial secondary emission standard by 0.5mg/l, and the total cyanide after advanced treatment of cyanide in step 6 was 1.25, which is lower than the industrial secondary emission standard by 0.5mg/l, and the total treatment time was 8 hours.
Example 3:
example 1 was repeated with the same procedure as described except that the gas to liquid ratio in steps 3 and 4 was adjustedto 300 and the other technical parameters and steps were the same as in example 1 except that step 3 was carried out for 2 hours and step 4 was also carried out for 2 hours.
Example 3 after the above process, the recovery of precious metals such as gold and silver reached 95.08% in step 1, the recovery of cyanide in the barren solution was 99.68% in step 3, the regeneration of sodium cyanide from thiocyanate was 86.76% in step 4, the overall recovery of cyanide was 94.81%, the arsenic concentration after neutralization of arsenic in step 5 was 0.08mg/l lower than the industrial secondary emission standard of 0.5mg/l, the overall cyanide after advanced treatment of cyanide in step 6 was 0.12 lower than the industrial secondary emission standard of 0.5mg/l, and the overall treatment time was 6 hours.
Claims (6)
1. A method for regenerating sodium cyanide from a cyanide-containing and thiocyanate-containing solution is characterized by comprising the following steps:
step 1 is the recovery of precious metals: cleaning 6-16 mesh coconut shell carbon activated carbon in a carbon washing tank, grinding corners, sieving carbon powder, filling granular carbon into three adsorption columns connected in series, and feeding a barren solution with the particle size of 8-10m3Flow rate is fed into two parallel acidification-aeration generation reaction kettles through three adsorption columns connected in series by virtue of an original barren solution pump;
step 2 is pretreatment: the lean solution pretreatment adopts a heating method, the defoaming agent-the long carbon chain of the cyclohexene oxide contained in the lean solution is damaged when the temperature reaches 60 ℃, and the heating method of the lean solution has two modes, namely, the electric heating mode and the gas-liquid jet aeration mode heating mode by utilizing the residual high-temperature air quantity of a main fan of a biological oxidation plant at the gas-liquid ratio of 200: 1 are adopted until the temperature is raised to 60 ℃, and the electric heating is stopped;
step 3 is to recover cyanide: an acidification-jet aeration generation-alkali liquor absorption method is adopted, wherein the absorption liquid adopts a sodium hydroxide solution with the concentration of 10-30%, the fillers adopted by the absorption tower are phi 25 and phi 50 stepped rings or polyhedral hollow ball fillers, and the spraying density of the absorption liquid is 10-15 m3/(m2H); acidifying the barren solution, wherein the optimal temperature is 30-40 ℃ when jet aeration occurs;
step 4 is the regeneration of sodium cyanide from thiocyanate: the method comprises the steps of oxidizing thiocyanate by a hydrogen peroxide method, generating jet aeration and absorbing alkali liquor, wherein the absorption liquid adopts 10-30% of sodium hydroxide solution, the fillers adopted by an absorption tower are phi 25 and phi 50 stepped ring or polyhedral hollow ball fillers, and the spraying density of the absorption liquid is 10-15 m3/(m2H); oxidizing thiocyanate by a hydrogen peroxide method, wherein the optimal temperature is 30-40 ℃ when jet aeration occurs; for treatingThe hydrogen oxide is added in an amount of at least 1.8 kg per kg of thiocyanate;
step 5 is arsenic treatment: the arsenic treatment adopts a lime milk neutralization method, the neutralized arsenic is precipitated in the form of ferric arsenate, and the pH value is 9.5-10;
step 6 is cyanide advanced treatment: the cyanide was oxidized by the hydrogen peroxide method, in which case the concentration of hydrogen peroxide was 0.2kg/m3After the barren liquor is deeply treated, the barren liquor is precipitated in a precipitation tankThe post-filtrate is returned to the cyanidation process.
2. The process of claim 1, wherein the regeneration of NaCN from a cyanide-containing thiocyanate-containing solution is carried out in the presence of a catalyst comprising: the thiocyanate is mainly from a cyanide leaching process of sulphide ores, wherein the cyanide process comprises gold leaching; electroplating or coal conversion; gold is recovered from the ore.
3. The process of claim 2, wherein the regeneration of NaCN from a cyanide-containing thiocyanate-containing solution is carried out in the presence of a catalyst comprising: the thiocyanate comes from the thiocyanate formed as an unnecessary by-product in industrial production and metallurgical industry, and the thiocyanate formed in the cyanidation process of the thiocyanate, gold and silver ores, concentrates, tailings and residues in sewage discharged from the industrial production of steel.
4. The process of claim 1, wherein the regeneration of NaCN from a cyanide-containing thiocyanate-containing solution is carried out in the presence of a catalyst comprising: the main sources of hydrogen peroxide are liquid analytical reagents, liquid industrial reagents, solid calcium peroxide, sodium percarbonate and other solid reagents that release hydrogen peroxide in aqueous solution.
5. The process of claim 1, wherein the regeneration of NaCN from a cyanide-containing thiocyanate-containing solution is carried out in the presence of a catalyst comprising: the pH of said thiocyanate contact medium is sufficiently low to ensure that it is maintained relative to CN-HCN is the predominant form in media, withpH less than 7.0.
6. The process of claim 1, wherein the regeneration of NaCN from a cyanide-containing thiocyanate-containing solution is carried out in the presence of a catalyst comprising: the hydrogen peroxide agent is added after the cyanogen-containing and thiocyanate-containing solution is acidified.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101759274B (en) * | 2010-01-11 | 2012-01-04 | 长春黄金研究院 | Recycling and harmless treatment method for cyaniding tailing slurry |
| CN104549147A (en) * | 2014-12-23 | 2015-04-29 | 昆明理工大学 | Preparation method and application of activated carbon for recycling gold |
| CN104876365A (en) * | 2015-05-28 | 2015-09-02 | 长春黄金研究院 | High-concentration cyanogen-contained tailing slurry treatment method for gold industry |
| CN112125320A (en) * | 2019-06-25 | 2020-12-25 | 湖南能也科技发展有限公司 | Method for desalting water from barren liquor or barren liquor generated in gold extraction process by cyanidation |
| CN113044857A (en) * | 2020-12-30 | 2021-06-29 | 重庆柒兴克米科技有限公司 | Production process and device for preparing high-purity sodium cyanide or potassium cyanide with high yield |
-
2005
- 2005-05-10 CN CNB2005100167778A patent/CN100515944C/en active Active
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101759274B (en) * | 2010-01-11 | 2012-01-04 | 长春黄金研究院 | Recycling and harmless treatment method for cyaniding tailing slurry |
| CN104549147A (en) * | 2014-12-23 | 2015-04-29 | 昆明理工大学 | Preparation method and application of activated carbon for recycling gold |
| CN104549147B (en) * | 2014-12-23 | 2017-05-10 | 昆明理工大学 | Preparation method and application of activated carbon for recycling gold |
| CN104876365A (en) * | 2015-05-28 | 2015-09-02 | 长春黄金研究院 | High-concentration cyanogen-contained tailing slurry treatment method for gold industry |
| CN112125320A (en) * | 2019-06-25 | 2020-12-25 | 湖南能也科技发展有限公司 | Method for desalting water from barren liquor or barren liquor generated in gold extraction process by cyanidation |
| CN113044857A (en) * | 2020-12-30 | 2021-06-29 | 重庆柒兴克米科技有限公司 | Production process and device for preparing high-purity sodium cyanide or potassium cyanide with high yield |
| CN113044857B (en) * | 2020-12-30 | 2023-05-23 | 重庆柒兴克米科技有限公司 | Production process for preparing high-purity sodium cyanide or potassium cyanide with high yield |
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| Publication number | Publication date |
|---|---|
| CN100515944C (en) | 2009-07-22 |
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