Gold extraction in gold ore

January 02 05:07:36, 2020

Flotation is suitable for processing single coarse grained iron ore natural gold. The crushed ore enters the ball mill and is finely ground into a flotation. In the flotation, sodium carbonate is used as a regulator to float the gold. At the same time, the butyl xanthate and the amine black medicine are used as a supplement to separate the gold ore powder from the slag and produce gold concentrate powder. Amalgam flotation is suitable for treating natural gold inlays with coarser grain sizes and stored in pyrite and other sulfide ores. Different from single flotation, after the grinding, the mercury plate is added for gold recovery, and the recovery rate can reach 30-45%. The slurry after the amalgamation is floated by the overflow of the classifier. In order to produce mercury mercury better, adding a certain concentration of sodium carbonate, caustic soda, etc. during grinding can make the mercury recovery rate of 70%. Gravity beneficiation uses the difference in the ratio of gold to other minerals for flotation. The greater the difference in specific gravity, the easier it is to separate. The gold-bearing ore is placed in a cylindrical sieve, and the ore is flowed through high-pressure water. The gravel sand larger than the sieve hole is transported into the tailing mine through the slippery belt and the belt; the ore than the sieve hole is input into the 1-3 section through the male distributor. The jig is fed into the shaker through the 3-stage jig concentrate, and is coarse, fine, and sweeped to produce fine sand ore. This method is mostly used for quicksand mines, and finely divided ores are also applicable.

The charcoal method is the most advanced gold extraction method in the world in the 1980s. It is better used in the treatment of gold-bearing limonite oxidized ore. In 1983, China National Gold Corporation decided to transform the beneficiation process of Shaoguan Gold Mine, citing the new process of carbon extraction from the United States. The carbon slurry method performs adsorption of activated carbon while oxidizing and leaching to increase the leaching rate of gold. The process includes: two-stage closed-circuit crushing, two-stage grinding, and the overflow product of the trimmer--200 mesh accounts for 95%, and then enters the thickener, and the concentration of the slurry is concentrated from 18-20% to about 42-45%, and then The buffer tank enters the leaching adsorption tank for leaching operation, and is adsorbed by activated carbon made of coconut shell to obtain the final product carrying gold charcoal. The tailings are completely sieved with high frequency to recover the gold in the crushed activated carbon, and then the cyanide-containing tail liquid is treated with liquid chlorine. Gold recovery is obtained by analytical, electrolysis, pickling, and the like. The high-concentration cyanide and high alkalinity are analyzed, and the gold in the gold-loaded carbon is analyzed under high temperature and high pressure, and the deposited solution is sent to the electrolytic recovery. The electrolytic cell uses steel wool as the cathode and stainless steel as the anode to adsorb gold on the steel wool. The analyzed activated carbon is washed with hydrochloric acid, with calcium carbonate and other impurities, and finally regenerated in a rotary kiln returned to 600 °C. The process was analyzed in 1986-1987. The leaching rate in 1987 was 5.73 percentage points lower than the 1986 five-month average, which was 81.36%. And the leaching rate fluctuates greatly every month, most of you 33%, up to 98.4%. The reason is that the content of sulfide and copper in the mine has an increasing trend from domestic and foreign tests in January and May of 1984. The increase of silver , aluminum and copper is also significant, affecting the leaching of the carbon slurry process. effect. Therefore, in 1987, a flotation process was reformed to treat some of the copper-bearing sulphide ore by flotation, which not only utilized the original flotation series of idle equipment, but also ensured the leaching rate of the carbon slurry method.

After smelting process for producing a variety of mineral ore powder of gold, silver, and an oxidizing agent is added KNO3 and borax. When the temperature of the furnace rises to 700 °C, the hair gold melts, the temperature of the furnace rises to 1000 °C, the melt begins to boil, the slag liquid floats, and the incandescent bright gold sinks calmly. When the furnace temperature is warmed to 1250 ° C -1350 At °C, the surface brightness of the slag liquid becomes dark, and the slag liquid is removed several times to produce pure gold. The overall process is to oxidize and remove compounds such as excess sulfur in the melt by melting. Electrolytic direct smelting This method is adopted by Shaoguan Gold Mine, which directly smelts gold and silver gold with steel wool as the cathode. Due to the original gold obtained by this method, gold and silver are not easy to separate. Silver is not priced when it is sold, and steel wool is mixed with slag at a time, and the cost is too high. Now it is changed to washed electrolytic steel wool, which has gold and silver mud. The general grade is 22-28% gold, 15-20% silver. When gold and silver are separated, silver, copper, iron and other slag enter the solution, while gold does not. Dissolved, present in a reddish brown state, and then the gold mud is washed, dried and smelted together with the solvent.

Angular contact Ball Bearings

 

Angular Contact Ball Bearing has high limit rotational speed, they can carry radial load and axial load simultaneously, they can also withstand purely radial load. The axial load carrying capacity depends on the magnitude of contact angle and increases with increasing contact angle.

Structures

1. Non-separable angular contact ball bearings

This inner ring and outer ring of this type of bearings cannot be separated and comprises following structures:

Contact angle α=15°      counter bore on outer ring,7000Ctype

Contact angle α=25°      counter bore on outer ring,7000ACtype

Contact angle α=40°      counter bore on outer ring, 7000B type

2. Four-point contact ball bearings

This type of bearings is separable bearings. Whereof, QJ0000 type has two-piece inner ring and QJF0000 type has two-piece outer ring. Their contact angles are same as 35°.When received no load or pure radial load, the steel balls of the Ball Bearing contact with the four points of the rings. When it is received a pure axial load, the steel balls perform a two-point contact with the ring. In addition, besides the axial load from both directions, this kind of bearing can take torque-load as well.

3. Double row angular contact ball bearings

This kind of bearings can accommodate radial loads as well as axial loads acting in both directions; they can also take loading moment. They can restrain the axial displacement from both directions of the shaft or housing; the contact angle is 30° (or 40°)

Permissible tilt angle

There is only a little inclination between the inner ring and outer ring of angular contact bearings, the permissible tilt angle varies according to the internal clearance when the bearings are operating, the bearing dimensions, internal design, force and loading moment received by the bearings. The value of the maximum permissible tilt angle should be able to ensure that no much extra stress to be generated inside the bearings.

The tilt angle existing between the inner ring and outer ring will influence the bearing service life. Meanwhile, the running accuracy is decreased down and noise increased.

Tolerance and clearance

The tolerances of general angular contact bearings are class normal P0, class P5 and P6. Class P4 and P2 are applicable to machine tool spindles and bearing amount in pairs.

Clearance of single row angular contact bearing is decided by the contact angle, which is guaranteed by manufacturing.

Axial clearance of Four-point contact ball bearings is listed in table 1.

Cage material

Generally, the cage of angular contact bearing is pressed cage of steel sheet or brass cage, and it is solid brass cage for two row angular contact bearing.

Dynamic equivalent radial load

Single-row angular contact ball bearings with a contact angle of 15°

Single bearing or bearing in pairs(7000 C.7000 C/DT)

Fa/Fr≤e         Pr=Fr 

Fa/Fr>e          Pr=0.44Fr+YFa

Back-to-back and face to face arrangements(7000 C/DB.7000 C/DF)

Fa/Fr≤e         Pr=Fr+Y1Fa       

Fa/Fr>e          Pr=0.72Fr+Y2Fa    

Single-row angler contact ball bearings with a contact angle of 25°

Single bearing or bearing in pairs(7000 AC.7000 AC/DT)

Fa/Fr≤0.68      Pr=Fr             

Fa/Fr>0.68       Pr=0.41Fr+0.87Fa   

Back-to-back and face to face arrangements(7000 AC/DB.7000 AC/DF)

Fa/Fr≤0.68      Pr=Fr+0.92Fa       

Fa/Fr>0.68       Pr=0.67Fr+1.41Fa    

Single-row angular contact ball bearings with a contact angle of 40°

Single bearing or bearing in pairs (7000 B.7000 B/DT)

Fa/Fr≤1.14      Pr=Fr             

Fa/Fr>1.14       Pr=0.35Fr+0.57Fa   

Back-to-back and face to face arrangements(7000 B/DB.7000 B/DF)

Fa/Fr≤1.14      Pr=Fr+0.55Fa      

Fa/Fr>1.14       Pr=0.57Fr+0.93Fa   

Four point contact ball bearings with a contact angle of 35°

Fa/Fr≤0.95      Pr=Fr+0.66Fa      

Fa/Fr>0.95       Pr=0.6Fr+1.07Fa    

Double-row angular contact ball bearings with a contact angle of 45°

Fa/Fr≤1.34      Pr=Fr+0.47Fa      

Fa/Fr>1.34       Pr=0.54Fr+0.81Fa   

Static equivalent radial load

Single-row angular contact ball bearings with a contact angle of 15°

For single bearing or bearing in pairs(7000 C.7000 C/DT)

 

P0r=0.5Fr+0.46Fa   

P0r<Fr  P0r=Fr

For back-to-back and face-to-face arrangements (7000 C/DB.7000 C/DF)

P0r=Fr+0.92Fa

Single-row angular contact ball bearings with contact angle of 25°

For single bearing or bearing in pairs (7000 AC.7000 AC/DT)

P0r=0.5Fr+0.38Fa  

when P0r<Fr  let P0r=Fr

For two bearings in back-to-back and face-to-face arrangements

P0r=Fr+0.76Fa

Single-row angular contact ball bearings with contact angle of 40°

For single bearing or bearing in pairs

P0r=0.5Fr+0.26Fa   

when P0r<Fr  let P0r=Fr

For two bearings in back-to-back and face-to-face arrangements

P0r=Fr+0.52Fa

Four point contact ball bearings

P0r=Fr+0.58Fa

Double-row angular contact ball bearings with contact angle of 45°

P0r=Fr+0.44Fa

Fr  Actual radial load of the bearing.

Fa   Axial load of the bearing

The values of e .Y .Y1 .Y2  see Table 2.

Table 1   Axial internal clearance of four point contact ball bearings

                                        μm

Nominal bore diameter  d

mm

C2 clearance

Standard clearance

C3

clearance

C4

clearance

Over

To

Min

Max

Min

Max

Over

To

Min

Max

10

18

40

 

60

80

100

 

140

180

220

 

260

18

40

60

 

80

100

140

 

180

200

260

 

300

15

26

36

 

46

56

66

 

76

96

115

 

135

55

66

86

 

96

116

136

 

156

176

195

 

215

45

56

76

 

86

96

116

 

136

156

175

 

195

85

106

126

 

136

156

176

 

196

216

235

 

275

75

96

116

 

126

135

156

 

176

196

215

 

255

115

146

166

 

176

196

216

 

236

256

295

 

335

105

136

156

 

166

176

196

 

216

236

275

 

295

145

186

206

 

216

236

256

 

276

296

335

 

355

 

Table 2   Calculate Coefficient

                           Î¼m

e

Y

Y1

Y2

0.172

0.345

0.689

1.03

1.38

2.07

3.45

5.17

6.89

0.38

0.4

0.43

0.46

0.47

0.5

0.55

0.56

0.56

1.47

1.4

1.3

1.23

1.19

1.12

1.02

1

1

1.65

1.57

1.46

1.38

1.34

1.26

1.14

1.12

1.12

2.39

2.28

2.11

2

1.93

1.82

1.66

1.63

1.63

Dw is the diameter of the rolling element

Angular Contact Ball Bearing

Machined Cage Angular Contact Ball Bearing,Pressed Cage Angular Contact Ball Bearing,One Row Angular Contact Ball Bearing,Two Row Angular Contact Ball Bearing

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