The ore properties of porphyry gold deposits are complex, the gold occurrence states are diverse, the gold minerals are finely embedded, and they are mainly associated with feldspar, quartz, rhodochrosite and other gangue minerals. The beneficiation methods of porphyry gold deposits are complicated due to their complex characteristics. This article mainly introduces the characteristics of porphyry gold deposits and common beneficiation methods.
1. Gold ore embedded with fine particle size
The fine particle size of gold minerals is a distinctive feature of porphyry gold deposits. Not only that, the distribution of gold minerals in the ore is also particularly dispersed, which virtually increases the difficulty of mineral processing.
2. Gold minerals are closely associated with various gangue minerals
Gold minerals in porphyry gold mines are closely associated with a variety of gangue minerals, which also increases the difficulty of mineral processing. During the mineral processing process, effective methods must be adopted to separate gold minerals from gangue minerals, and at the same time, avoid over-grinding. Waste of resources.
3. Differences in mineral composition
Porphyry gold deposits in different regions vary greatly in mineral composition.
1. Coarse particle gravity separation-fine particle flotation method
Among the beneficiation methods of porphyry gold deposits, the asynchronous beneficiation process of "coarse-grained gravity separation-fine-grained flotation" has significant advantages. The specific process is as follows:
(1) Semi-autogenous grinding: After the raw ore is ground by semi-autogenous grinding, it is screened through a vibrating screen. The hard stones on the screen are returned to the grinding, and the slurry under the screen enters the slurry pool.
(2) Ball mill grinding and classification: The slurry in the slurry tank is pumped to a high-level hydrocyclone, and the sand flows to the ball mill for grinding, and water glass and sodium hexametaphosphate are added. The overflow product enters the mixing barrel, and enhanced collector and foaming agent 2 oil are added.
(3) Gravity separation operation: The ball mill grinding product is fed into the gravity separation equipment (such as a jig or centrifugal concentrator), and flushing water is added. The concentrate is the final gravity separation concentrate product, and the tailings are returned to the slurry pool and carbonic acid is added. Sodium slurry.
(4) Flotation operation:
The stirred slurry enters the flotation system and undergoes multi-tank rough selection. The foam concentrate in the first tank of rough selection directly enters the flotation concentrate slag slurry tank, and the foam concentrate in other tanks is merged and entered into the beneficiation operation.
Scavenging: Add enhanced collector and 2 oil, the concentrate returns to roughing, and the tailings are final flotation tailings.
Selection: No flotation agent is added, the tailings are returned to rough selection, and the concentrate is the final flotation concentrate.
(5) Advantages of this process:
It realizes the early recovery of coarse visible gold minerals that are first dissociated during the grinding and classification process, avoiding the problem of accumulation and loss of coarse gold in the grinding and flotation system;
The gold minerals that are easy to float are quickly floated, and the first tank rougher concentrate is directly used as the flotation concentrate product, avoiding the problem of deterioration of the quality of the rougher concentrate due to prolonged flotation time;
The proposed enhanced collector can improve the recovery of fine gold minerals and gold-containing barren gangue intergrowths; Fourth, the sodium carbonate addition point is moved forward to the slurry pool, and water glass and sodium hexametaphosphate are added to the ball mill, which increases the action time of the flotation reagents, expands the time interval of the reagents, and reduces the mutual influence between the flotation reagents.
2. Roasting-cyanide leaching beneficiation method
For fine-grained altered granite porphyry oxidized gold ore, the following beneficiation processes can be used:
(1) Grinding: The ore enters the ball mill for grinding, the grinding concentration is 50-60%, and the ore pulp with a grinding fineness of less than 0.074mm and a content of 90-95% is obtained.
(2) Roasting: After the ground slurry is densely dried, it is placed in a rotary kiln for oxidation roasting treatment at a temperature of 600-900℃ for 6-12h.
(3) Cyanide leaching: Adjust the slurry concentration to 30-50%, add protective soda lime and sodium cyanide, and stir and leach.
(4) Solid-liquid separation: The slurry after cyanide leaching is lightly washed and filtered, the filtrate is the precious liquid, and the filter cake is the leaching residue.
(5) Coconut shell charcoal pretreatment: Coconut shell charcoal with a particle size of 6-40 mesh is selected for pretreatment, and coconut shell charcoal with a particle size of 6-16 mesh is selected after screening.
(6) Carbon slurry adsorption process: The pretreated coconut shell charcoal is wrapped with gauze and placed in the precious liquid for an adsorption time of 8-16 hours to obtain gold-loaded charcoal and barren liquid.
Advantages of this process: It solves the problem that flotation and gravity separation methods are difficult to separate, avoids the adverse effects of fine mud during the grinding of oxide ore, and has the characteristics of simple process flow, strong adaptability, and high gold leaching rate.
