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Home > Case Studies> The Production Line of All Sliming Cyanidation CIP Process

The Production Line of All Sliming Cyanidation CIP Process

All sliming cyanidation CIP method to gold smelting process refers to all the gold ore grinding pulverized pulp (-200 mesh content of 90 ~ 95%), the first cyanide leaching, and then use activated carbon absorb charcoal gold directly from the slurry. The process includes the following steps: preparing raw materials, stirring cyanide leaching activated carbon countercurrent adsorption, carrying gold carbon desorption, carrying gold carbon desorption electrowinning, gold mud separating and refining melting smelting casting Ingot, activation and regeneration of activated carbon and cyanide-containing wastewater treatment in seven operating stages (Figure 1)

CIP gold extraction process production flow chart-Beijing Hot Mining Tech Co.,Ltd

1. Material preparation

1.1 Crushing

Generally use two open broken or two closed-circuit crushing process (Figure 2), gold-containing material through the pre-screening, coarse material on the screen into a crushing, crushing and then through the second section of the broken into the grinding operation . The purpose of the operation to control the crushing ratio of each section and to ensure that the second section of the size of broken products, the use of two closed-circuit process to ensure a more rigorous grain size. The general crushing ratio of 3 to 5, too large or too small are not conducive to improving the crushing efficiency, reduce costs and protect equipment. The size of second crushing products should be less than 1 ~ 1.5cm, the maximum not more than 3cm, can be adjusted through the crusher discharge port size to control. Production to implement the "pre-screening, and more broken less grinding" principle.

1.2 Grinding stage

More use of two closed grinding process（Figure 3）The first stage of the closed-circuit grinding process consists of grid-type ball mill and spiral grading. The second stage of the closed-circuit grinding process consists of overflow type ball mill and hydrocyclone. The pre-grading and inspection grading of the second-stage closed-circuit grinding process will help improve the grinding efficiency and ensure product fineness. Crush good gold material after the first paragraph of the closed-circuit grinding process, the pulp in the -200 mesh content of 55 to 65%.After the second stage of the closed-circuit grinding process after the slurry in the -200 mesh material content can reach 90% to 95% or more, in line with the whole mud cyanide process fineness requirements. This section mainly controls the grinding concentration, the overflow concentration and the fineness of the overflow. General grinding concentration: the first paragraph of 75% to 80%, the second paragraph of 60% to 65%; overflow concentration: the first paragraph of 20% to 25%, the second paragraph of 14% to 20% Flow fineness (-200 mesh content): the first paragraph is 55% to 65%, the second paragraph is 90% to 95%.

The control of the grinding concentration mainly through the regulation of water supply, to the amount of ore and return to sand, etc., if the grinding concentration is high, then increase the amount of water, minus the amount of ore, increase the ratio of sand, and vice versa. The control of the overflow concentration can be controlled by the overflow water supply, the height of the overflow weir, the ore inlet, the discharge port, the overflow port size, etc., and the control of the overflow fineness will adjust the height of the overflow weir, And the amount of steel balls, ball ratio, return to the sand ratio, grinding concentration, overflow concentration. In short, in the grinding operation of the technical parameters are interrelated, complement each other, mutual restraint, so in the process of adjusting the control to consider and coordinate the role.

1.3 Debris removal operations

Multi-level debris removal process. The first stage of debris removal process is located in the crushed ore, to manually detect the debris and other debris in the ore. The second stage of the debris removal operation is located in the spiral classifier overflow, the use of aperture of 2 ~ 3mm plane sieve plate. The third level of debris removal operations in the hydrocyclone to the mine before the use of 20 mesh sieve plate. The fourth level of debris removal operations in the concentrated dehydration before the use of 24 to 28 mesh curved screen.

This section of the operation must be promptly removed sieve debris, and often check the use of the screen and found that the timely replacement of damage to ensure that the pulp debris quality.

Pulp in the cyanide leaching before the need for strict debris removal is due to the ore into the wood chips, gravel, fuse, woven bags of debris, slag and other debris, likely to cause the hydrocyclone into the slurry mouth and sedimentation mouth, thickener The existence of gravel will increase the wear of activated carbon; the presence of wood chips will be dissolved and gold caused by the loss of gold, wood chips may also be converted into brittle in the regenerative kiln Carbon and reduce the yield of gold. Therefore, the debris removal operation is very important, according to the order from coarse to fine as much as possible to set up debris screen layer.

1.4 Pulping stage

Mainly in the thickener, more use high-performance thickener, single-layer thickener or multi-layer thickener. The pulp with the pulp concentration of 40% ~45%, the pulp PH value of 10~11, while the slurry transported by the grinding operation to the pulp concentration of 14% ~20%, PH value of 7~10. This section of the operation by adjusting the concentration of the bottom of the flow and the amount of flocculant to control the slurry concentration, by adjusting the amount of lime added to the ball mill or the concentration of sodium hydroxide in the thickener to control the pulp PH value, so that the next leaching Adsorption requirements.

2. Stirring the cyanide leaching stage

Stirring cyanide leaching, also known as pre-dip operation, generally by two efficient energy-saving leaching tank(slot 1 and 2) in series. Slurry transported from the upper operation to the No. 1 slot, and then from the No. 1 slot into the No. 2 slot. This operation is mainly to control the concentration of cyanide ions in the leaching slurry and oxygen content. The suitable cyanide ion is 0.05% to 0.08%, which is controlled by adjusting the dosage of sodium oxide. Oxygen content of the slurry is usually used to indicate the amount of inflation and inflation pressure, the general charge of 0.02, the inflation pressure of 100Kpa. Production is usually in the pulp surface evenly dispersed 5 ~ 15mm diameter small bubbles are appropriate, by adjusting the total valve and the tank inflation valve to control the inflation.

3. Adsorption of activated carbon phase

Activated carbon adsorption phase is also known as the edge of the edge of the suction operation. The so-called counter-current adsorptions is through the mention of charcoal, string of charcoal, charcoal and make activated carbon through the mention of carbon to enhance the operation of the direction of the opposite with the flow of pulp. This operation is generally composed of five energy-efficient absorption tank (No. 3, No. 4, No. 5, No. 6, No. 7) in series and five charcoal devices. 2, No. 6, No. 7 adsorption tank, loaded with gold from the No. 3 slot raised, and then from the No. 4 slot string to No. 3 slot, No. 5 slot To 4, 6 to 5, 7 to 6 and 7 to the new tank. This section of the operation of the main control technology are: cyanide concentration, oxygen content, the bottom carbon density, charcoal speed, charcoal, carbon gold content, tail gold content, tailings grade.

3.1 Concentration of cyanide in pulp

And slightly lower than the stirring oxidation leaching stage, 0.02% ~ 0.05%, and there are 3 trough to the subsequent trough gradually reduced, No. 7 tank minimum 0.02% to 0.03%. By adjusting Sodium cyanide to add the amount to control.

3.2 The oxygen content of pulp

It is lower than agitation leaching, controlled by adjusting the gas valve of those tanks.

3.3 Bed carbon density

Bed carbon density is the content of activated carbon per liter in pulp, usually 10-15g/L. In order to ensure the recovery of gold, the bed carbon density of No.7 tank is usually slightly higher, it is 15-20g/L. The density of bed carbon can be controlled by adjusting the amount of carbon adding, string carbon and carbon extraction.

3.4 String carbon velocity

String carbon velocity, also known as string carbon frequency, refers to the number of string carbon in unit time. Based on the study of the mass balance of gold in the adsorption system, the product of the string carbon velocity and the gold loaded amount of carbon is a constant. In order to maintain the appropriate gold loaded amount of carbon, it is necessary to select a certain string carbon velocity, usually one time per day.

3.5 Amount of string carbon

In order to maintain the balance of the total amount of gold in the adsorption system and to maintain the adsorption performance of the carbon in the tank, there should be a suitable percentage between the amount of string carbon and the amount of activated carbon stored in the tank, this ratio is 10 to 20% in general. Adjusting the length of the string carbon time can control the amount of the string carbon.

3.6 Gold loaded amount of carbon

Under the premise of ensuring the adsorption rate, the amount of gold loaded of carbon should be as high as possible, but the higher the amount of gold loaded, the more gold storage in the adsorption system, cash flow will be affected. So appropriate amount of gold loaded of carbon, reasonable string carbon system are important for the gold CIL plant. Generally the final gold content of gold loaded is 4 ~ 6g / kg, it can be adjusted by adjusting the amount of carbon extraction.

3.7 Gold content of tailing solution

The content of gold in the tailing solution is 0.02~0.1g/m³, if it is more than this value shows that there is some problem with the adsorption of activated carbon, adsorption rate is reduced, it can be controlled by increasing density of bed carbon, reducing the content of gold-loaded carbon or shorten the time of string carbon.

3.8 Tailing grade

The tailing grade is 0.2~0.3g/t in general, the maximum will not more than 0.5g/t. Adjusting and control of this technology index is complicated, based on existing equipment and technology, it can be controlled by Improving grinding fineness, reducing the slurry concentration, reducing capacity or extending leaching time.

In a word, the technical indicators are not isolated, they are interrelated, effect of any adjusting method is not unilateral. So we should find out the best control measures according to the specific circumstances in the production, in order to improve the total recovery of gold and achieve the best economic benefit.

4.Gold loaded carbon desorption electrowining stage

The operation of desorption and electrowinning of gold loaded carbon mostly adopts the process of heating and pressuring desorption, high temperature and atmospheric pressure electrowining combined with closed circuit,there is a relatively mature degree of automation control desorption electrowinning device.The configuration of desorption and electrowining effusion : the mixed solution of 1% NAOH and 1% NaCH.

The anode of the electric trough is the stainless steel plate with a hole ,cathode is a special high quality steel.During the operation of production,as long as we often observe the various instruments and touch or rotating equipment on various buttons or knobs to to control the temperature, pressure, flow rate, voltage, and desorption time on the operation of desorption and electrowining , then it will reach the ideal desorption effect.The general desorption temperature is 105℃, the pressure is 2000Kpa, the time is 14-16h, (start timing when the desorption column temperature reached 70℃).

The electrowinning temperature is 70 -80, the voltage is 3-4V, and the flow rate of the liquid is 300L/h.The above technical parameters are easy to control and stable.

5.The gold mud of separation and purification,melting pouring ingot stage

In this stage, the work should be carried out under strict supervision and protection.According to the formal method of gold and silver smelting,should fire smelting electrowinning gold mud at first,to make the gold and silver into unrefined gold and silver ingot,then concentrate from the gold and silver ingot further separation and purification .However,in order to speed up the turnover of funds,you can also directly use separation and purification ,melting pouring ingot way.

5.1 Separation and purification of gold mud (acid method):

1) Add a certain amount of hydrochloric acid to the gold mud at first,adequate reaction to remove residual steel wool and other parts of the splash metal,

After filtering and washing, add a certain amount of nitric acid,adequate reaction to remove most of silver and other metals,then filer and wash again.

This step is to control the amount of acid, reaction time and washing degree.The amount of acid is related to the amount of gold mud impurity,the reaction time should be determined according to the reaction conditions and the actual reaction situations.But the general reaction time should be no less than 2-3h.

Washing degree is crucial,each wash must be neutral,hot wash would be more faster.

2)In the washed gold mud, gradually add into 3-4 times the weight of aqua regia,stirring gold solution,heating to boil in the later period,making gold into solution with ionic condition,Then filtering gold solution and sediment.This step should be noted that the initial adding aqua regia, the reaction is intense,we should prevent the overflow of gold solution.

The reaction time of dissolving gold is generally not less than 2-3h,we should pay attention to observe the change of sediment color.

3) To the gold solution by adding an excessive amount of anhydrous sodium sulfite can obtain sponge gold.Erenow,gold-containing solution should be acid-drived at first to PH =6-7.

When plus anhydrous sodium sulfite, gradually added a small amount until excess,at the same time,continue to heat and stir.

5.2 The melting ingot of spongy gold(coke furnace)

1) Adding borax 10%-15%,sodium carbonate 5%-10%,glass flour 3%-5% into the spongy gold,after mixing into the preheated graphite crucible and put into the furnace to smelting.

Total melting time 1.5-2.0 h,melting temperature 1200-1300 ℃.This step should pay attention to control the furnace temperature and smelting time, and often observe the crucible placed and the melting of the material within the pot.

2）After melting sufficiently, remove the crucible with a clamp and pour the melt into the mold.This step should be noted that the mold must be preheated ,

and the inside surface even smoked a layer of 1mm black smoke.Casting should be noted that the first slow and then fast after the slow sequence, casting time is 10 seconds.

After getting out the gold ingot,first soak in dilute nitric acid or hydrochloric acid solution for about 5-10min, then wash the acid with water, and then soak in alcohol for a moment, take out and wipe dry,gold fineness 99.9%.

6. Activation and Regeneration Stage of Activated Carbon

6.1 Acid activation regeneration

Each circulation of activated carbon, adsorption-deabsorption, needs acid activation regeneration. The method is by using 3%-5% hydrochloric acid mixing with gold charcoal in pickling container, after that washed with clean water, then wash with NaOH solution until it becomes neutral. The purpose of acid activation regeneration is to remove the acid soluble content such ascalcium, magnesium and sodium that adsorbing on activated carbon. It should be payed special attention that during the procedure of acid treatment, there’ll be virulent hydrocyanic acid. Necessary measures must be taken to protect safety.

6.2 Pyrogenic process activation regeneration

Generally speaking, every 5-10 circulation of activated carbon needs the treatment of pyrogenic process activation regeneration. The pyrogenic activation regeneration is processed in steel tube pits. There’re two heating zone in the steel tube pit, the temperature of first zone is 600℃, the steam atmosphere is generated. The temperature of the second zone is above 650℃, the carbon achieves activation regeneration in this zone. The operation method is adding the wet carbon from the feeding end of steel tube pit, the carbon is transferred to the discharging end during rotation. After cooling by air, the carbon could be used. The main purpose of pyrogenic process activation regeneration is to remove the influence of organic fouling on activated carbon by pyrogenic treatment process.

7. Cyanide Wastewater Treatment Stage

This operation consists of two sewage treatment tanks, and is treated by chlorine alkali method, namely adding the bleaching powder into the sewage treatment tank under the alkaline condition, then mix and oxygenolysis the cyanide in the sewage, and finally reaches the purpose of detoxify, refine and remove pollution. In actual application, by adjusting the amount of bleaching powder, the cyanogen in sewage could be reduced below 0.5mg/L, then the sewage will be pumped into the setting pond or tailings pond to degradation naturally.

Contact us:

Serena Fu

Kira Zhang

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serena.fu@hot-mining.com

kira.zhang@hot-mining.com

Skype

Serena20140924

kira.zhangjing

Whatsapp +86 151 0833 3341
+86 152 8105 1932

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Home > Case Studies> The Production Line of All Sliming Cyanidation CIP Process

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	Serena Fu	Kira Zhang
E-mail	serena.fu@hot-mining.com	kira.zhang@hot-mining.com
Skype	Serena20140924	kira.zhangjing
Whatsapp	+86 151 0833 3341	+86 152 8105 1932