CIL Process

Cil is an advanced supported fully viscous cyanide cyanide observed through zinc substitutes, which thickens before leaching, leaching and adsorption, gold-loaded carbon and electrode action, pickling and gold smelting. The best feature of the cil process is that the leaching is performed at the same time. In this way, the stirring tank can be retained, thereby saving money. In recent years, it has been widely used in newly built leaching plants.

The cil technology is suitable for treating oxidized gold ore with materials with low sulphur content and dirt content. For gold ore containing too much silver, this is flawed. Generally, the share of gold and silver should not exceed 1:5. In China, the only situation where cil exists is: ph = 10-11, but the attention of cyanide is not 0.0.5%, the particle size of activated carbon is 1.0-3.35mm, and the form of carbon is coconut shell activated carbon. Therefore , The slurry concentration is 40-55%.

1 Training Before Leaching

Before leaching, in addition to crushing, grinding and classification, it is also desirable to perform some operations, such as chip cleaning, thickening of the slurry and therefore adding detergent.

1.1 Particles-Removal Operation

Sawdust, grass roots and different particles in the slurry can effortlessly reason clogging of the pipe and screen, and consequently the sawdust will absorb gold, so it ought to be eliminated earlier than leaching. Typically , twice of particles-elimination operations are vital in grinding procedure, respectively, within the first and consequently the second stage grinding type overflow. Intermediate frequency linear vibrating displays are widely used as debris-removal gadget, within the first debris-removal operation, spiral display and drum screen are also can been seen, particles-elimination sieve length need to be as small as feasible,however need to ensure the slurry can go with the flow thru the sieve without problems.

1.2 Thickening Operation

The grinding overflow fineness of ordinary gold ore is 85-95% smaller than 0.074mm, grinding overflow fineness of flotation listen is as much as 99% smaller than zero.047mm. The overflow attention is clearly 18-22%, which is not suitable for direct leaching, so thickening is required.

High efficiency thickener is widely used because of its small footprint and excessive operation performance.

1.3 The Addition Of Detergent

To be able to cut back the fouling of the activated charcoal floor and carbon segregation display screen and different gadgets, a particular quantity of detergent are frequently delivered before leaching

2. Leaching And Absorption

Leaching and absorption are simultaneous is that the finest function of cil technique. Its section variety is typically 6-10, because the cyanide is introduced within the first tank, and tiny gold is leached, maximum cil plant will upload the activated charcoal from the second one tank to the final one. Carbon segregation screen is organized in every absorption tank to split the carbon and slurry. Slurry drift mechanically from the number one tank to the last one at the same time as the activated charcoal waft reversely. It means the activated charcoal is positioned into the slurry at the last absorption tank and gold-loaded activated charcoal is taken out at the primary absorption tank. After screening and washing, the gold-loaded activated charcoal are going to be despatched to the desorption operation. After absorption, the gold grade within the tailing answer are going to be 0.01-zero.03g/m³.

2.1 Leaching

In the course of the leaching, cyanide will react with gold and silver, and convey cyanide complex with gold and silver. Lime is hired for maintaining the ph, so on save you the assembly of toxic gas hcn. Within the excessive widespread automation cil plant, a hcn gasoline detector is commonly mounted within the leaching and absorption vicinity.

Oxygen is needed for the response of the cyanide with gold and silver. In idea, zero.4g oxygen is were given to react one gram gold, however, in practice the amount is a ways large, thanks to that gold ore continually has diverse steel sulfides, which can also devour oxygen to react with cyanide . In real production, the medium strain air of 100kpa is employed to go through the hole shaft of the agitator. Air glide is generally controlled and measured by means of a rotor float-meter.

In current years, the 2 key technical and economic index that enhance leaching and reduce the intake of cyanide are paid attention by using engineers and specialists, cilo manner starts to return into view. Cilo system has these advantages as under:
(1) Accelerating leaching kinetics, decreasing leaching time, and on occasion growing leaching price of gold and silver
(2) Lowering intake of sodium cyanide
(3) Higher leaching result in very best gold ore than cil system
(4) Effective leaching of ores containing higher oxygen consuming minerals

For example, one gold mine in hebei , undated the cil procedure to cilo procedure. They failed to exchange any device only accelerated an oxygen compressor unit to change the first compressor . The leaching time became shortened from 36-42h to best approximately 20h, and therefore the leaching charge turned into additionally accelerated by zero.89%, the intake of cyanide become additionally stored 0.27g in keeping with ton. Way to the shortening of leaching time, the assembly capacity of the first leaching gadget has improved from 300t/d to 643t/d, which has created apparent monetary benefits.

Peroxide or peroxide changing the compressed gas are able to do the intention of cilo, however the perfect impact need to be decided via take a look at and simulated production experiment.

2.2 Absorption

Generally used activated charcoal is coconut shell activated charcoal , it’s higher adsorption overall performance and abrasion resistance. Carbon segregation display screen must be hooked up inside the go out of each absorption tank, and consequently the display mesh usually pick out 24 mesh 304 stainless-steel screen.

The general shape of the carbon segregation screen is spherical and v, linear vibrating sieve and other form display also can be seen in some cil plant.

2.2.1 Primary Factors Affecting The Adsorption Of Activated Charcoal
The primary factors affecting the adsorption of activated charcoal contains the adsorption potential, electricity, particle length of the activated charcoal .

After long distance transportation, there are lots of broken carbon or powdered carbon, which require to be pretreated earlier than use to exclude its have an impact on.

2.2.2 Influence Of Slurry Residences
The primary have an effect on of slurry homes consists of coarse sand and sawdust, slurry concentration and viscosity, organic remember in slurry, ph price of slurry, carbonaceous ore;

2.2.3 Influence Of Operating Parameters
The working parameters consist of aeration quantity, aeration mode, cyanide attention, and carbon retention within the manner then on.

2.3 Check And Manage

In the manufacturing technique, test employee is vital to test the slurry attention, ph value, cyanide concentration, carbon attention inside the slurry, those parameters need to be examined as soon as each two hours . In the manufacturing unit with excessive degree of automation, on line monitoring and automated adjustment of slurry attention, ph and cyanide attention are available. The operators were given to check the air glide, carbon segregation display screen, tank floor all the time.

3. Desorption Of Gold-Loaded Carbon And Electro-Deposition

Gold-loaded carbon and slurry are lifted through carbon pump or air-lifter to separation sieve (the freshest sieve is rotary vibrating sieve). Gold-loaded carbon and slurry are separated via water at the sieve floor, then gold-loaded carbon is shipped to carbon tank and consequently the slurry and water circulate the number one absorption tank.

There are several desorption methods. In china, the overall utility methods are zadra desorption approach, warmth and high desorption approach (hereinafter stated as hthp technique) and fundamental strain desorption approach (hereinafter noted as ip approach).

3.1 Zadra Desorption Method

On this manner,the desorption answer includes 1% caustic soda and zero.1% cyanide answer . The desorption time is 24-72h at air stress of 85-95 c. This approach is easy , the investment and value is low, however the time is lengthy and consequently the working environment is negative.

3.2 HTHP Approach

The desorption answer of hthp approach is 0.1% cyanide and 1% caustic soda answer . The specified temperature is a hundred and fifty-a hundred and seventy℃, and consequently the pressure is 0.35mpa, the desorption time is merely 4-6h, the approach conditions are frequently executed. This method has benefits of lower consumption of chemical substances, speedy desorption speed, and quick cycle of carbon cycle. However during this approach, the pregnant answer got to be cooled earlier than discharging to forestall boiling and splashing;

3.3 Ip Approach

Ip technique is analogous to hthp method, however the electro-deposition is found within the stress machine, no longer got to fear approximately boiling and splashing, and pregnant answer does not to be cooled earlier than electro-deposition, and consequently the desorption answer become simplest 5% caustic soda answer. The desired temperature is 150℃, and consequently the stress is zero.5mpa, the desorption time is set 6h, electro-deposition voltage is 2.5-3.0v, and electro-deposition cutting-edge is 250a. This approach is maximum commonly used.

4. Regeneration Of The Activated Charcoal

After desorption, the activated charcoal want regeneration to get better its proper adsorption overall performance.

The regeneration of the activated charcoal includes acid-washing and thermal regeneration. Acid-washing regeneration is to soak the activated charcoal in five% dilute aqua fortis answer. Regular with the meeting practice reception and abroad, acid-washing regeneration can simplest take away a neighborhood of inorganic substance at the activated charcoal , recover the iodine cost and carbon tet of the activated charcoal , additionally as lower the ash content of activated charcoal . The adsorption potential and adsorption price of carbon are not completely progressed. After several instances acid-washing regeneration, thermal regeneration is required .

The thermal regeneration process includes four steps: drying, carbonization, carbonization and cooling. After thermal regeneration, the adsorption capacity and adsorption fee of carbon are going to be fully recovered, and therefore the adsorption hobby is probably getting ready to or reached the brand new carbon level.

5. Predominant System In Cil Plant

5.1 The Practise Gadget Earlier Than Leaching

The gadgets for preparation before leaching include crushers, conveyors, vibrating screens, ball mills, classifiers, chip removal screens, thickeners and slurry pumps.

5.2 Gadget For Leaching And Absorption

The gadget for leaching and absorption consists of leaching tank, absorption tank, carbon-elevate system, carbon segregation display and safety display

6. Equipment For Desorption And Electro-Deposition

The gadget for conventional zadra desorption and electro-deposition method includes: desorption column, electric powered fireplace , electric powered-depositing tank, clear out, device , corrosion resisting pump.

The device for ip method carries:desorption column, electric powered hearth , electric-depositing tank, filter, corrosion resisting pump.