It is well known that when the high arsenic and sorghum gold ore is directly cyanated, the gold is difficult to be leached. The ore must be pretreated by oxidation to destroy its structure, so that the gold wrapped by the metal sulfide is exposed to obtain a better leaching effect. At present, the pre-oxidation treatment methods for this type of ore mainly include roasting method, hot pressing oxidation method, and sodium sulfide wet leaching method, and the alkaline water chemical pre-oxidation method is rarely reported. This work is aimed at this aspect of research on a gold ore in Qinghai. First, the nature of the ore Crushing the ore consists of quartz vein altered rock type and two types, with a strong characteristic alteration mineralization, sericite, silicification like pyrite. Metal ore minerals natural gold, pyrite, galena, sphalerite, stibnite (0.1 to 4.0%), arsenopyrite (15%); gangue minerals quartz, sericite followed , dolomite, chlorite, etc. The poisonous sand and pyrite are surrounded by quartz; the stibnite is filled between quartz particles or cracks, which contains poisonous sand and pyrite; the poisonous sand contains pyrite. The natural gold particle size in the ore is 0.074 to 2.0 mm, which is 21%, less than 0.074 mm, and invisible gold, which is 79%. Among the sulfides encapsulating natural gold, pyrite accounts for 79.49%, stibnite accounts for 15.99%, and arsenopyrite accounts for 4.52%. The results of ore chemical analysis are shown in Table 1. Table 1 Ore chemical analysis results% Au Ag Cu Pb Zn Bi Sb As S TFe Fe 13.14×10 -4 1.75×10 -4 1.7×10 -3 2.4×10 -3 4.5×10 -3 0.01 2.54 1.03 1.51 3.88 4.20 Fe 2 O 3 SiO 2 CaO MgO K 2 O Na 2 O Al 2 O 3 P 2 O 5 MnO 2 C 0.87 16.88 0.70 0.48 2.00 2.16 13.32 0.20 0.06 0.444 0.701 It can be seen from Table 1 that the valuable metals in the ore are mainly gold, and the content of the secondary ruthenium also reaches the level of comprehensive utilization. The content of low-cost iron in ore is 4.8 times that of high-priced iron, indicating that the ore is a reducing primary ore. The mass fraction of SiO 2 in the ore is lower (16.88%), and the mass fraction of elements such as K, Na and Al is higher. The ore contains more clay minerals and has poor permeability; the ore contains harmful elements such as arsenic, antimony, sulfur and carbon, and gold is encased by gold-bearing minerals (pyrite, arsenopyrite, stibnite), which is extremely difficult to leach. Gold ore. Second, the exploration test The ore quality is 25g, the particle size is -325 mesh, 98.6%, the alkali (NaOH) dosage is 10%, the mixed oxidant is 2% A+1% B, and pre-oxidized for 4 days at 30-35 °C. Then, according to the ratio of 1t ore and 1.4kg NaCN, the liquid solid product mass ratio is 2:1, pH=10～11, and room temperature is leached in a conventional manner for 24 hours. After the leaching, the leaching slag is washed once, and the mass fraction of gold in the leaching residue is measured to calculate the leaching rate of gold. The results show that the gold leaching rate is 82.01%, and the gold content in the slag is reduced to 2.57×10 -4 . When the ore is directly cyanated, the gold leaching rate is almost zero, and after chemical pre-oxidation with alkali (NaOH) water, the cyanide leaching rate increases the gold leaching rate to 82.0%. Water chemical pre-oxidation-cyanide immersion gold process. This is because the alkaline solution contains an appropriate amount of mixed oxidant (A+B), which can oxidize the ore and chemically react with the metal sulfide (pyrite, arsenopyrite, stibnite) in the ore to decompose the sulfide mineral. The gold is exposed to dissolve the gold. Third, the condition test (1) Effect of the amount of alkali (NaON) and mixed oxidant (A+B) The amount of alkali (NaOH) and mixed oxidant was changed. The other conditions were the same as those in the exploratory test. The test results are shown in Table 2. Table 2 Effect of alkali and mixed oxidant addition on gold leaching rate Numbering /% Slag /(g·t -1 ) Gold leaching rate /% A B OH-12 OH-31 OH-34 OH-32 10 7 10 13 0 1.4 2.0 2.6 0 0.9 1.0 1.3 5.79 2.88 2.29 1.90 55.94 79.66 83.90 85.80 (B) the impact of pre-oxidation time The pre-oxidation time was changed, and other conditions were the same as those of the exploration test. The test results are shown in Table 3. Table 3 Effect of pre-oxidation time on gold leaching rate Numbering Preoxidation time /d Slag Gold leaching rate /% OH-7 OH-27 OH-28 OH-29 OH-30 1 2 4 6 9 6.26 3.89 2.57 2.80 2.75 52.36 71.46 82.01 79.71 80.58 (3) Influence of ore particle size The ore particle size was changed, and other conditions were the same as those of the exploration test. The test results are shown in Table 4. Table 4 Effect of ore particle size on gold leaching rate Numbering Particle size/mesh Slag Gold leaching rate /% OH-52 OH-53 OH-54 -160 -200 -325 4.82 3.06 2.38 64.42 77.74 82.34 (4) The effect of pre-oxidation temperature The temperature at the time of pre-oxidation was changed, and other conditions were the same as those of the exploration test, and the test results are shown in Table 5. Table 5 Effect of pre-oxidation temperature on gold leaching rate Numbering Particle size/mesh Slag Gold leaching rate /% OH-11 OH-28 OH-34 OH-49 14～21 30~35 50~55 65~70 4.2 2.57 2.29 1.59 70.34 82.01 83.90 88.53 (V) Effect of sodium cyanide dosage on gold leaching rate After pre-oxidation of the ore under optimal conditions, the gold is leached by conventional cyanidation. Change the amount of sodium cyanide, other conditions are the same as the exploration test, the test results are shown in Table 6. Table 6 Effect of sodium cyanide dosage on gold leaching rate Numbering Particle size/mesh Slag Gold leaching rate /% OH-58 OH-57 OH-49 800 1200 1400 2.16 1.90 1.59 84.87 86.58 88.53 (6) Comprehensive test According to the above conditions, the selected optimum conditions were tested, and the ore was first subjected to hydrochemical pre-oxidation and then leached by conventional cyanidation method. As a result, the gold leaching rate was as high as 91.56%, and the effect was satisfactory. (7) Changes in mineral composition In order to investigate the changes of ore components after alkaline water chemical pre-oxidation treatment-cyanide leaching, the mineral components of the leaching slag were identified. The results show that the main minerals in the slag are quartz (53.5%), chlorite (18%), sericite (14%), dolomite and a small amount of carbonate minerals (3.5%). The metal minerals are mainly limonite ( 9.0%), followed by a very small amount of pyrite (<0.5%) with a small amount of powdered sulphur or sulphate (1%). It can be seen that after the ore is oxidized under alkaline conditions, the composition changes significantly. Most of the sulfides (pyrite, arsenopyrite, stibnite) are decomposed, and the wrapped gold is exposed, thereby making gold Can be leached. Fourth, the conclusion High arsenic, sorghum, gold sulphide (pyrite, arsenopyrite, stibnite) coated refractory gold ore, suitable for oxidation under mixed conditions with mixed oxidant and then cyanide leaching. This method is simple, has little environmental pollution, and gold can be fully leached. After the ore is subjected to water chemical pre-oxidation and re-cyanide leaching under alkaline conditions, the composition and process mineralogical properties have changed significantly. The mineral composition of the leaching residue is mainly gangue minerals, and most of the sulfides are decomposed, leaving only a small amount. The main machine consists of a bed, a double-layer precision workbench, a sliding mechanism for adjusting the top seat, a sliding assembly for the top seat, a moving and driving system for the table, a rotating and driving system for the spindle, a rotating and adjusting mechanism for the parts, a matching balance, a cover frame, and an electrical numerical control part. CNC quenching transformer can be used to move up and down the lifting table at a constant speed, chuck or thimble fixed roll or shaft rotation at a constant speed, inductor water quenching while. The machine tool adopts advanced numerical control technology, through programming can realize continuous scanning quenching, quenching at the same time, section continuous scanning quenching, section quenching at the same time. The machine tool is driven by a stepper motor controlled by a programming controller, while controlling the heating equipment and workpiece rotation as well as liquid injection. The body is made of steel plate and channel steel structure, and the guide rail is made of cylindrical linear rolling guide. The workpiece moving drive screw is ball screw, and the top moving drive is T screw. CNC,Quenching Machine,CNC Quenching Machine,CNC Machine Ningbo Yufeng Electronics Co., Ltd , https://www.yufengheating.com
(NaOH) (mixed oxidant) /% (Au)
The test results show that the gold leaching rate is very low without the addition of mixed oxidant under the same conditions of sodium hydroxide. As the amount of sodium hydroxide and mixed oxidant added increases, the gold leaching rate increases. In a strongly alkaline medium, the exposed gold portion is oxidized to AuO 2 - , AuO 3 3 - goldate and transferred to the solution. The base and mixed oxidizing agent are preferably used in an amount of 10% and 2% A + 1% B. (Au)/(g·t -1 )
The results show that the gold leaching rate increases with the pre-oxidation time, but the pre-oxidation time is too long (6d) or more, and the gold leaching rate decreases. The treatment time is preferably 4d. (Au)/(g·t -1 )
The test results show that the gold leaching rate increases with the decrease of ore particle size. When the ore particle size is -325 mesh and 98.6%, the leaching result is better. This is related to the fine size of the ore and the full exposure of gold. (Au)/(g·t -1 )
It can be seen from Table 5 that the temperature has a greater influence on the pre-oxidation of the ore. As the pre-oxidation temperature increases, the gold leaching rate increases. When the pre-oxidation temperature is raised to 65-7O °C, the gold leaching rate reaches 88.53%. For this reason, the temperature of the ore pre-oxidation treatment is preferably 65 to 70 ° C. (Au)/(g·t -1 )
The test results show that the ore is cyanidated by gold after chemical pre-oxidation, and the gold leaching rate reaches 88.53% under the condition of 1.4kg/t sodium cyanide.
Main configuration of quenching machine host:
1. Numerical control system control;
2, stepper motor drive;
3, ball screw transmission;
4, cylindrical linear guide, ball slider sliding;
5. Ac speed regulating motor drives the sprocket chain, and the optical bar rotates the workpiece;
6, AC reducer motor drive lead screw, lead screw is the top lifting;
7, solenoid valve control water spray;
8, equipped with control heating equipment plug.
Main features of quenching machine host:
1, the use of numerical control technology, with connection, at the same time, segment connection, segment at the same time and other quenching functions.
2, used for shaft, disk, pin, gear and other parts of the induction quenching.
3, can be configured with integrated quenching liquid circulation cooling system.
4, the use of profile structure body, high degree of automation.
Notes for CNC quenching machine tools: CNC quenching machine tools are used to heat quench or normalize large workpieces with industrial electric frequency, low voltage and large current. Use should comply with the safety rules of electricity.