The recovery of gold from complex gold - arsenic feedstocks depends to a large extent on the complete degree of arsenic removal at the beginning of the process. Vacuum pyrolysis is one of the most promising methods for arsenic removal from refractory sulfide concentrates.
This paper describes the results of industrial tests on flotation concentrates and re-election concentrates at a deposit in Siberia. These tests were carried out in a continuously operating vibrating vacuum pyrolysis apparatus under industrial production conditions. The vacuum pyrolysis unit was jointly developed by the Kazakh Academy of Mineral Processing , the National Institute of Rare Metals and the Central Asian Nonferrous Metals Scientific Research and Design Institute.
The composition of the concentrate used in the test is as follows: (%)
As Fc S SiO 2 CaO A1 2 O 3 MgO C
Flotation concentrate 1.8 6.50 5.09 45.54 0.28 12.66 - 16.7
Re-election of concentrates 15.9 35.66 32.44 8.52 0.71 1.78 1.0 4.85
Solutions of the vacuum thermal process flotation concentrate flotation concentrate size distribution (grain size, mm) as follows,%: + 2.5-6.81; 1.6-5.5 + -2.5; -1.6 + 0.63-4.4,; - 0.63 + 0.4 -4.2; -0.4+0.315-15; -0.315+0.20-2.8; -0.2+0.16-4.6; -0.16+0.1-21.8; -0.1+0.063-21.7; -0.063+0.05-11.6; -0.05-15.1.
Bulk density was 1.11 g / cm 3 (not scattered) and 1.34 g / cm 3 (scattered), concentrate the true specific gravity of 2.72 g / cm 3, the natural angle of repose of 48 °.
At a temperature of 650 ~ 700 ℃ and a residual gas pressure of 35 mm to 100 mm - Hg under conditions, we have carried out several tests. The day and night processing capacity of the unit fluctuated between 1 and 8 tons (Table 1).
Concentrated weight of kg | Processing capacity Kg/hour | pressure Millimetre mercury | Material temperature °C | Cinder obtained | Arsenic content in slag % | Arsenic volatilization rate % | |
kg | % | ||||||
272 | 28.40 | 70 | 690 | 213 | 78.30 | 0.21 | 90.80 |
320 | 42.20 | 100 | 670 | 250 | 78.10 | 0.28 | 87.80 |
809 | 71.50 | 50 | 640 | 633 | 75.20 | 0.17 | 92.60 |
182 | 80.70 | 60 | 660 | 142 | 78.00 | 0.18 | 92.20 |
413 | 33.00 | 35 | 660 | 323 | 78.20 | 0.22 | 90.40 |
The yield of the slag is 78.2% of the concentrate, and the arsenic content is 0.17~.28%.
The particle size composition (grain size, mm) of the slag is as follows, %: +0.63-1.8; -0.63+0.4-1.4; -0.4+0.315-1.2; -0.315+0.2-1.3; -0.2+0.16-2.2; -0.16 +0.1-17.1; -0.1+0.063-36.9; -0.063+0.05-17.6; -0.05-20.5.
Bulk density of 0.91 g / cm3, the true specific gravity of 2.74 g / cm 3, the natural angle of repose of 50 °.
In the vacuum pyrolysis process, the concentrate needs to undergo a certain degree of grinding and loosening. The material balance in the treatment of flotation concentrates and the distribution of arsenic in different products are listed in Table 2.
The soot yield was 6.40% of the concentrate fed. The arsenic content in the soot fluctuates between 0.5 and 3.7%. The reason for the increase in arsenic content in soot is that the heating in the cyclone is insufficient and uneven.
The yield of the condensate was 3.2%, wherein the arsenic content was 48.1%, the sulfur content was 13%, and the gold content was 4 g/ton.
Since there is no fine-grained soot trap in the vacuum pyrolysis apparatus, the condensate is heavily contaminated by soot (mainly carbon-containing components).
There is a certain difference between the feed material and the calculated material, which is mainly due to the mechanical loss caused by the exhausted flue gas and the presence of other volatile components in the concentrate. Flue gas is produced during the decomposition of carbonate and the partial oxidation of sulfur and carbon. [next]
Vacuum pyrolysis of re-selected concentrates The particle size composition (grain size, mm) of the re-selected concentrate is as follows, %: +2.5-4.95); -2.5+1.6-1.47; -1.6+0.63-1.89; -0.63+0.4 -3.27; -0.4+0.315-3.67; -0.315+0.2-12.17; -0.2+0.16-10.53; -0.16+0.1-29.17; -0.1+0.063-22.89; -0.063-9.99.
Concentrate bulk density was 2.81 g / cm3, the true specific gravity of 4.63 g / cm 3, the natural angle of repose of 35 °.
At a temperature of 700 ° C and a residual gas pressure of 40 to 100 mm Hg (5.33 to 13.33 kPa), a unit treatment capacity of 2.2 tons / day and night • meter 2 , a total of 1109 kg of re-election concentrate was treated. The material balance of the concentrate subjected to vacuum heat treatment for arsenic removal is shown in Table 2.
Product | Weight | Arsenic content% | Arsenic distribution rate% | |
kg | % | |||
Flotation concentrate | ||||
Concentrated concentrate | 1990 | 100 | 1.80 | 100.00 |
Cinder obtained | 1561 | 78.20 | 0.20 | 8.88 |
No. 1 cyclone dust collector | 106 | 5.31 | 0.51 | 1.50 |
No. 2 cyclone dust collector | 13 | 0.65 | 3.77 | 1.36 |
No. 3 cyclone dust collector | 8 | 0.40 | 3.00 | 0.67 |
Condensate | 64 | 3.21 | 48.10 | 82.20 |
total | 1752 | 87.77 | - | 94.60 |
Re-selection of concentrate | ||||
Concentrated concentrate | 1109 | 100.00 | 15.90 | 100.00 |
Slag obtained | 768 | 69.25 | 0.67 | 2.92 |
No. 1 cyclone dust collector | 9.5 | 0.86 | 10.55 | 0.55 |
No. 2 cyclone dust collector | 13.5 | 1.22 | 8.30 | 0.64 |
No. 3 cyclone dust collector | 6.0 | 0.54 | 11.20 | 0.38 |
Condensate* | 214 | 19.30 | 70.20 | 85.20 |
total | 1011 | 91.20 | - | 89.70 |
* - Part of the condensate falls into the piping of the vacuum system, so the result is somewhat low. | ||||
The arsenic volatility was 97% at a temperature of 700 ° C, a pressure of 100 mm Hg and a treatment capacity of 3 ton / day and night.
The slag yield was 69.3%, and the arsenic content was 0.67%.
The particle size composition (grain size, mm) of the slag is as follows, %: +2.5-5.4; -2.5+1.6-4.0; -1.6+0.63-2.3; -0.63+0.4-5.9; -0.4+02-22.0; +0.16-12.5; -0.16+0.1-23.6; -0.1+0.063-15.6; -0.063-8.7.
During the vacuum pyrolysis process, the particle size of the concentrate did not change significantly. The true specific gravity of the slag increased to 5 g/cm 3 , while the pseudo specific gravity decreased from 2.8 g/cm 3 to 1.93 g/cm 3 .
The yield of the condensate was 19.3%. It is in the form of a yellow powder. The arsenic content in the condensate was 70.2% and the sulfur was 28.7%. In terms of its chemical composition, this condensate is equivalent to realgar.
During the vacuum pyrolysis of the re-concentrated concentrate, approximately 99.8% of the gold remains in the slag, 0.2% of the gold is transferred to the soot, and only a trace amount of gold is present in the condensate.
The power consumption is 400~500 kW•hr/ton concentrate.
Industrial tests carried out show that, entirely possible to obtain a very high arsenic volatilization from gold ore flotation concentrates and reselection of arsenic pyrite, and can be obtained in a conventional method for processing as well as nontoxic slag Arsenic-containing condensate.
Direct Warping Machine
A-ZEN direct warping machine is a new-developed machine with advanced function. A brand new closed circuit tension technology, known as PID technology, is used on direct warping machine AZ118L type, and because of that, yarn tension stability and accuracy are both assured. Meanwhile, the computerized real-time monitoring system can detect beams` diameters in a accurate way.
Technical Data:
Warp Line Speed: 100-1,000m/min;
Beam Size: Φ21"*21", Φ30"*21", Φ40"21";
Control Way: Computerized real-time control;
Tension Roller: Real-time PID adjusts yarn tension in closed loop control;
Beam Up-and-down, Clamping and Brake: Pneumatically Operated;
Main Motor: 7.5KW AC-frequency controlled with constant linear speed and closed circuit;
Brake Torque: 1600NM;
Air Connection: 6 Bar;
Copy Precision: Beams` perimeters are recorded;
Maximum Counting Range: 99999 meters/circles.
Direct Warping Machine,Copy Function Warping Machine,Beam Waping Machine,Yarn Warping machine
CHANGZHOU A-ZEN TEXTILE TECHNOLOGY CO.,LTD , https://www.barmachinery.com