The abundance of gold in the earth's crust is very small, with a Clark value of only 5 x 10-7 g/t. The chemical nature of gold is very stable. The main mineral of gold in nature is natural gold (gold, density 17500~ l8000kg/m3). In addition to being produced in vein deposits, sand ore is also an important source of gold.
The gold ore beneficiation is mainly re-election, and the alluvial gold deposit is mainly used for gold mining vessels; the land gold is mainly used for chute and washing unit. In the sand deposit, gold is mostly granular and scaly, and exists in a free state. The particle size is usually from 0.5 to 2 mm. In rare cases, large particles of gold having a mass of several tens of grams are also encountered, as well as extremely fine gold particles that are difficult to distinguish with the naked eye.
The content of gold in the gold deposit is generally 0. 2 ~ 0. 3g / m3, the high density mineral content of density greater than 4000kg / m3 is usually only l ~ 3kg / m3. The maximum grain size of the gangue in the gold deposits is very different from that of the gold particles, even more than a thousand times. However, after screening the gravel containing no ore, it can still be selected without classification.
China's gold mining has a long history. The mining method is mainly based on gold mining vessels, accounting for more than 70% of total gold mining. Secondly, there are water gun mining and excavator open-pit mining. In some cases, underground mining is used. The gold mining vessels are flat-bottomed ships equipped with excavation mechanisms, sorting equipment and tailings conveyors. The typical gold mining ship structure is shown in Figure 1.
Gold mining vessels can float on natural water or in artificially digging pools. During production, the front excavation site is enlarged, and the selected tailings are filled in the goaf of the stern. According to the different construction of the excavator, gold mining vessels can be divided into four types: chain bucket type, cutter suction type, mechanical bucket type and grab type. The chain bucket consists of a series of buckets mounted on the chain, and the ore under the surface of the water is excavated by the rotation of the chain and sent to the screening equipment on the ship. The specifications of the chain bucket gold mining vessel are expressed in the volume of one bucket, between 50 and 600L. Small gold mining vessels of less than 100L, medium-sized gold mining vessels of 100-250L, and large gold mining vessels of greater than 250L. The ore dressing equipment on the ship mainly includes cylindrical sieve, slurry distributor, coarse grain chute, jig, trampoline and so on. The selection of the ore dressing process is related to the production capacity of the gold mining vessel and the nature of the sand mine. There are mainly three types shown in Figure 2. The typical processes adopted in China are the first two.
Figure 1 Schematic diagram of the gold mining ship
1 a bucket chain; 2 a bucket; 3 a roller; 4 a main transmission; 5 a circular sieve; 6 a mining funnel; 7 a phase; 8 a pump: 9 a winch; 10 a belt conveyor; 11 a wrong column; l2 a transformer; 13 a deck pulley; 14 a punt; 15 a front pole; l6 a rear mast: 17 a main frame; 18 a footbridge
Figure 2 Production process commonly used on gold mining vessels
(a) Fixed chute process
(b) slippery jigging-shake process
(c) Three-stage jigging process
The fixed coarse-grain chute process is to install transverse chutes and longitudinal chutes symmetrically on both sides of the cylindrical screen arranged along the hull. The ore excavated by the chain bucket is directly discharged into the cylinder screen, and the gravel is discharged onto the tailing belt and conveyed to the stern. This kind of process is simple and low in cost. It is applied more on small gold mining vessels, and the recovery rate of gold is not high, ranging from 58% to 75%.
The chute-jigging-shaker process is mostly used on small and medium-sized gold mining vessels. The chute is a fixed strip with a tape chute. The jig can be a trapezoidal jig, a side-by-side diaphragm jig, a circular and a rectangular jig. Shakers are available in industrial or medium size equipment. The final recovery rate of gold can reach 79% ~ 85%.
The equipment used in the three-stage jigging process is a jig, which is a common application process for large and medium-sized gold mining vessels. In the first section of the large gold mining vessel, two nine-chamber circular jigs can be installed, the second section is equipped with a three-chamber circular jig, and the third section is a two-chamber rectangular jig. A nine-chamber circular jig was installed in the first stage of the medium-sized gold mining vessel. The second and third sections were rectangular jigs and side-by-side diaphragm jigs. The recovery rate of gold can reach more than 90%.
The main sorting equipment of the centrifugal disc sorting process is a centrifugal disc sorting machine or a centrifugal gold cone. The working efficiency of the equipment is high, the floor space is small, and the recovery rate can reach 85% ~ 90%. It is one of the small and medium-sized gold mining vessels. A promising combination of processes.
In order to increase the production efficiency of the gold mining vessel, the heavy sand produced by the gold mining vessel (re-selection of the coarse concentrate) can be concentratedly transported to the onshore fixed selection plant for selection to separate the gold from other high-density minerals.
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1. Our History:
LITE Crane Co., LTD has focused on top quality Crane Parts for over 14 years in China. We started as a small operation, but now have become one of the leading suppliers in the crane industry in China.
Today, LITE Crane Co., LTD has been one of the top producers of quality crane and crane parts, such as: electric hoist, single, double girder bridge, gantry, grab, casting, explosion-proof crane series and accessories.
2. Our Factory:
LITE Crane Co., LTD is located in Xinxiang, Henan Province China. The company covers an area of 680 thousand square meters and owns more than 2700 employees. The annual sales of LITE Crane Co., LTD is 1.6 billion USD, there are more than 600 sales agencies at home and abroad and more than 180 middle& senior engineering and technical personnel who are in charge of design and development of all products and also own the development center of their new technology and products.
3.Our Product:
Our Products includes the following:
1, Crane accessories
2, Electric hoist
3, Single - beam cranes
4, Double - beam cranes
5, Bridge Crane
6, Gantry Crane
7.Lifting equipment and accessories
We supply crane products all over the globe to a wide range of companies worldwide.
4.Product Application:
The products are widely used in the following industry, such as power plants, nuclear power, water conservancy, tunnels, bridges, petrochemical, metallurgy, construction, open-air warehouse, wharf, workshop ...
5.Our Certificate:
Our company is a member of China Crane Association and vice chairman company of China Heavy Machinery Association. It owns the production licenses of electric hoist, single & double-girder crane, the safety of the approval certificate of manufacturing, installation and maintenance, the safety approval certificate of the manufacturing of 320T bridge crane, portal crane and 280Tcasting crane.
The company has passed the quality system certification of GB/T19001 -2008/IS09001:2008, the environmental management system certification of GB/T24001-2004/ISO14001:2004 and the occupational health and safety management system certification GB/T28001-2001.
6.Production Equipment:
There are 1600 units of all kinds of processing equipment which can independently accomplish all the processes such as milling, digging, grinding, pulling, boring, rolling, drilling, punching, cutting, bending, welding, testing and heat treatment.
7.Production Market:
Our products are sold to more than 30 provinces, municipalities and autonomous regions in China, and also exported to Australia, Vietnam, India, Thailand and some Southeast Asian countries. The annual sales of double-girder and portal cranes is more than 3600 units, more than 23000 units single-girder cranes, about 23000 units single-girder & double-girder electric hoist and accessories. The production and sales of the single-girder cranes has lead the nation for seven consecutive years and the per capita output and economic benefits are among the best in the same industry.
8.Our service:
Besides our existing molded products, LITECrane Co., LTD also can produce products according to the drawings or samples from our customers. We control the product quality critically for every step during the manufacturing from custom.
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Shandong Lite Electrical Co.,Ltd , http://www.chinacranegroup.com