Activated carbon regeneration technology (1)

1 preface

    I researched that activated carbon regeneration technology can be traced back to 1989 . At that time, companies outside the drainage tailings recovery of gold has been dissolved in Hebei province wide industrial tests pointed gold mine in northern China, received a large number of low-grade gold-loaded carbon. The gold-bearing charcoal obtained from the wastewater containing only 0.03 to 0.05 mg/L of gold and containing extremely high impurities does not exceed the gold grade. 500g / t, and impurities such as Cu, Fe, etc. than 10kg /t , calcium carbonate calcium sulfate and calcium silicate content is higher, therefore, the use of gold-carbon desorption equipment at that time can not effectively desorb gold, therefore, began to study activated carbon desorption technology, in the process, found on activated carbon Impurities have a great influence on desorption, so pretreatment with hydrochloric acid, and then desorption with our desorption equipment, achieved a good desorption effect. Moreover, the activated carbon after desorption is used for gold adsorption, which is repeated 4 times. This fully demonstrates the importance of wet regeneration of activated carbon and the effectiveness of hydrochloric acid for wet regeneration. However, it is not enough to rely solely on wet regeneration, because in the process of adsorbing gold by activated carbon, the organic matter contained in the liquid phase such as engine oil, flotation agent, and organic matter in minerals are more easily adsorbed on activated carbon. During the process of regeneration and desorption of gold, it will not be completely desorbed from the carbon. They occupy a large amount of active surface area on the activated carbon and block the pores, so that the performance of the activated carbon is greatly reduced. It is necessary to rely on high temperature regeneration to eliminate the carbon activity of such impurities. Impact.

Therefore, we began to develop activated carbon high-temperature regeneration equipment. Over the years, we have studied various foreign activated carbon regeneration equipment. Such as the early rotary kiln ( coke heating or electric heating type), the later vertical multi-tube regenerative furnace (heating medium with gas and fuel oil), boiling regenerative furnace (fuel for coke, etc.), electric heating internal heating type Regeneration equipment. Among them, Minturn regeneration equipment in South Africa has been researched the most and deepest. The focus on South Africa's Minturn recycling equipment is purely accidental. An introduction to the carbon pulp factory in the Foreign Gold Reference describes several activated carbon regeneration equipment. The introduction of South Africa's Minturn regeneration equipment is also accompanied by a device structure diagram, which has a strong interest in this equipment. Not only because this kind of regenerative equipment was invented from the world famous South African mine and metallurgy society, but also because of its simple structure, high degree of automation, low power consumption, long service life, and the ability to make products with different processing capabilities. Small footprint and easy operation. In addition, it is easier to collect information about Mintek in South Africa. For example, the Changchun Gold Research Institute Library has “ E & MJ ” magazine, which often has the company’s technology and product reports; the company also has Internet access. The webpage, its product introduction is more detailed and timely.

2 structure of activated carbon

    Structure and properties of the activated carbon and graphite somewhat similar, flake graphite is composed of carbon atoms arranged in a regular hexagonal layers of laminated together. And activated carbon is not as regular as graphite. According to X -ray studies, there are two types of structures of activated carbon. The first type consists of basic crystallites with a structure similar to graphite. The second is a stable structure in which the carbon hexagon forms a cross-linked solid lattice. Many activated carbons contain both types of structures. Activated carbon produced by high temperature activation, microcrystalline structure predominates.

    During the activation process, the material removes many of the carbides and carbon between the basic crystallites, and also removes a portion of the carbon from the substantially microcrystalline graphite layer, creating a number of pores.

    The pores are large and small, and the shapes are different. According to the pore size, activated carbon can be divided into three categories:

Large hole type             Transition hole (or mesoporous) type       Microporous

500 to 2000 angstroms 100 to 500 angstroms 8 to 100 angstroms

    Macroporous activated carbon allows adsorption of certain organic macromolecules and as a catalyst deposition carrier. The microporous structure is suitable for gas adsorption and adsorption of certain inorganic complex ions from solution. For the adsorption of activated carbon, the most important is micropores. Because they have a large specific surface area and specific volume.

    Accounting for 10 Angstroms pore size greater proportion of coconut shell charcoal, coal char interstitial pore size distribution mainly in the range of 10 to 2000 angstroms.

    The elemental composition of activated carbon is mainly carbon, and also contains a small amount of hydrogen and oxygen. Some of the elements that bind to the surface of the activated carbon may exist in the form of functional groups. It is now found that functional groups commonly found in activated carbon include carboxyl groups, phenolic hydroxyl groups, quinone carbonyl groups, common type lactones, fluorescein-type lactones, carboxylic anhydrides, cyclic peroxides and the like. They are located on the edge of the fracture of the ring network in the activated carbon layer.

Shell or core activated carbon for gold absorption is usually activated at a temperature of 700 to 800 °C. There are also a certain number of hydroxyl groups and phenol groups on the surface. Therefore, it can be used in both acidic and alkaline media.

3 performance of gold extraction activated carbon [ 1 ], [ 2 ], [ 3 ]

    Activated carbon for gold extraction has the following physical and chemical properties:

Physical properties

Particle density (determined by mercury replacement method) 0.80 ~ 0 .85g /ml

Bulk density 0.48 ~ 0 .54g /ml

Pore ​​size 20 ~ 10 angstroms

Pore ​​volume 0.70 ~ 0.80ml / g

Ball hardness (ASTM) 97 to 99%

grain     Degree 1.18 to 2 .36mm

gray     2 to 4%

Moisture content 1 to 4%

Chemical adsorption characteristics

Surface area (N ₂ BET) 1050 ~ 1200m ² /g

iodine       Value 850 ~ 1150mg / g

Carbon tetrachloride value 60 to 70%

benzene       Value 36 to 40%

Hydraulic Support System Seals Kits

Hydraulic Support System Seals Kits