Gold heap leaching with an alkaline solution as sodium cyanide leaching solution, leaching the ore is not strong multi-acidic rocks. If the acidity of the rock is strong, the washing pretreatment is carried out until the pH of the washing water flowing out of the washing is ≥9, so that sodium cyanide leaching can be performed. Therefore, its fouling situation is divided into two stages to discuss, one is the heap washing stage, and the other is the leaching stage. If lime granulation heap leaching and pre-cyanide (sodium cyanide solution are added during granulation), the heap washing is no longer carried out. The acidity of the ore, the scaling in the heap washing stage is very noteworthy, although the washing water of the heap does not enter the aftertreatment system, it will not cause the equipment and pipeline fouling of the carbon adsorption system, but if it is not handled properly, it will The surface of the ore heap, the inside of the heap and the sprinkling system are severely fouled. The wear of the nozzle is also the most serious at this stage. The white coating on the surface of the heap is basically formed at this stage. In addition to gold, the components in the gold ore heap leach liquor mainly have the following substances: 1. Humic acid salt Due to the multi-line oxidized ore in the heap leaching ore, close to the surface, the weathered ore contains organic matter, especially the humic acid content of humic acid is high. These substances dissolve in alkaline solution to form humate, which can be Activated carbon or resin adsorption; under acidic conditions, humate will form a large molecular weight humic acid precipitate, deposited in the pores of the adsorbent, resulting in a decrease in the specific surface area of ​​the adsorbent, a decrease in adsorption capacity, and often an adsorption-desorption Equipment and pipe fittings are fouled. Second, carbonate compounds It is a major factor in fouling in gold mine heap leaching. It is well known that there are complex equilibriums of carbonic acid and bicarbonate compounds in aqueous solutions, generally expressed by the following reaction formula: CO 2 +H 2 O H 2 CO 3 HCO 3 - The above three reaction formulas can be integrated into CO 2 +H 2 O Since one CO 2 can only produce one H 2 CO 3 , one H 2 CO 3 can only ionize one HCO 3 − , and one HCO 3 − can only ionize one CO 3 2 − , so in one system, regardless of How does the concentration of CO 2 , HCO 3 - , and CO 3 2 - change, and the sum of the three concentrations is always equal to a constant C, or also because If the three fractions in (A) are used as the dependent variable, [H + ] as the independent variable, and the three equations are solved, the CO 2 in different systems [H + ] (or pH) can be obtained. The content of HCO 3 - and CO 3 2 - . K 1 (4.45 × 10 -7 ) and K 2 (4.96 × 10 -11 ) at 25 ° C are known numbers, using three fractions as the ordinate and pH as the abscissa, which is obtained as shown in Fig. 1. The relationship between the carbonic acid compound and the pH in an aqueous solution at 25 ° C. Figure 1 Relationship between ionization of carbonic acid and pH (25 ° C) It can be seen from Fig. 1 that when the pH is lower than 4.4, only CO 2 is present in the solution. When the pH is > 8.35, there is no CO 2 in the aqueous solution; when the pH is 4.4 to 12.0, the bicarbonate ion HCO 3 - can exist. When the pH value is 8.35, the content of HCO 3 - is the highest, accounting for 98%; when the pH is > 8.35, there is CO 3 2 - in the aqueous solution. The gold heap leaching solution has a pH of 9-11, so a large amount of CO 3 2 - is present in the leaching solution. Third, calcium and magnesium ions Calcium and magnesium ions in the heap leaching of gold from the two aspects, one, most heap leaching of gold instead of caustic lime for protection alkali solubility of lime is not large, but the closed circulation is heap leaching, long-term use, and the solution The calcium in the continually increases. Second, and most importantly, calcium and magnesium ions are mainly derived from ore. Because of the presence of organic matter in the ore, the oxidation and decomposition of the organic matter will produce CO 2 , especially in the washing stage, the CO 2 produced consumes the alkali of the leaching solution, CO 2 + OH - = HCO 3 - , and the pH of the leaching slag is lowered. And dissolves the carbonate minerals in the ore to form a large amount of bicarbonate Ca(HCO 3 ) 2 and Mg(HCO 3 ) 2 . This soluble bicarbonate combines with CO 3 2 - to form CaCO 3 or The scale of MgCO 3 . In addition, some studies have pointed out that there is ion exchange between sodium ions and calcium and magnesium ions in the ore during leaching, that is, the calcium and magnesium ions in the ore under the sodium ion exchange in the leaching solution not only cause calcium and magnesium ions to enter the solution. Fouling is formed, and when a large amount of clay is present, the sodium ions cause the clay to swell, which also causes the original porosity of the heap to decrease and the permeability to deteriorate. Four, silicate SiO 2 dissolved in acid, but slightly soluble in alkali due to the constant, so there are some silicate ore leaching solution with the silicate, aluminosilicate heap leaching of gold in contact with alkaline solution, they form complex For example, a salt of metasilicate H 2 SiO 3 , ortho silicic acid H 4 SiO 4 , polysilicic acid H 2 Si 2 O 5 or the like. These silicates have low solubility, little ionic state, and mostly colloids. Further, depending on the pH, when pH=6, the amount of SiO 3 2 - is only 0.01 mg ∕ L, and when pH = 7, 0.1 mg ∕ L, pH = 10.5, the amount of dissolution is greatly increased. The amount of SiO 2 in the leachate of the US Zotman heap leaching field is 18-23 mg ∕L. The silicate compound in the leachate is very unstable, especially the colloidal silicic acid compound, which tends to be the initial nucleus of the scale. It is easy to scale on the surface of the heap as well as the carbon adsorption and resolution system. Five, iron compounds Alkaline leaching solution does not dissolve iron very much, but when the ore is acidic, if it contains a large amount of humic acid, the situation is different. There is more Fe 2 + in the leaching solution, because in alkaline solution, Fe 2 + is easily oxidized by oxygen in the air to form Fe 3 + , which leads to the formation of Fe(OH) 3 precipitate. Manual Welding Fume Exhaust System
1. Product description:
Manual welding fume exhaust system is an entire dust and smoke extraction system for multi-welding station workshop. For industrial central dust extraction, we usally have cantilever type fume extraction system for manual welding, hoodus suction type welding fume extraction system for manual and robotic welding, room type fume extraction system for robotic welding, blow suction type fume extraction system for manual or/and robotic welding.
2. Moland Product Series
Moland Portable Fume Extractor series contain of MLWF50, MLWF70, MLWF100, MLWF360, MLWF120, MLWF200, MLWF280-basic, MLWF280S, MLWF290, MLWF300, MLWF300A, MLWF350, MLWF350D, MLWF400, etc.
Except portable fume extractors, we also supply stationary fume extractors (MLWF350-dust bucket type, MLWF500-6T, MLWF500-6T dust bucket type, MLWF500-9T, MLWF800, MLWF800-dust bucket type, MLWF1000, MLWF1500, MLWF2000, MLWF3000, MLWF3500, MLWF4000). The electric control cabinet can be seperated from main equipment for convenient operation when the main equipment is placed outdoors.
Grinding dust extractors are our another dust extraction product series, which contain of downdraft table (MLWF100D, MLWF150D, MLWF200D, MLWF320-DM, MLWF180, MLWF380, MLWF480) and grinding cabinet (MLWF900). The grinding cabinet is usally equipped with telescopic or fixed grinding room, to form a semi-closed space to control dust and smoke spread. It also improves the filtration efficiency with low air volume and energy consumption.
3. R&D
In order to provide advanced products, our R&D department develops 3 to 5 new products every year, and irregularly improves the performance, appearance, and installation methods of existing products.
4. Certification
All our products are approved by CE, ISO9001, ISO14001, utility model patent, design patent, Program copyright, etc.
5. Exhibition
Moland participates at least 5 industry exhibitions each year.
6. Central Fume Extraction System
1) Cantilever type fume extraction system
Cantilever dust removal can be used for manual welding conditions where the work stations are evenly distributed and the span is small. The smoke and dust generated by each welding station can be effectively absorbed at the dust generation point, and will not pollute other parts of the workshop. The skeleton of the suction arm is similar to a human arm and can hover in a space within a certain length. The outer layer of the suction arm is a temperature-resistant hose, which not only prevents the hose from being burned by sparks, but also ensures the flexibility of the movement of the suction arm. A unique rotating structure is designed on the position of the Suction Hood to ensure that the suction hood can be aligned with the welding position in any orientation, so that the suction arm can effectively capture the smoke and dust generated during the welding process. The advantage of the suction arm capture is that it can be close to the place where the smoke is generated, and the collection effect is better.
2) Hood suction type fume extraction system
Cantilever dust removal can be used for manual welding conditions where the work stations are evenly distributed and the span is small. The smoke and dust generated by each welding station can be effectively absorbed at the dust generation point, and will not pollute other parts of the workshop. The skeleton of the suction arm is similar to a human arm and can hover in a space within a certain length. The outer layer of the suction arm is a temperature-resistant hose, which not only prevents the hose from being burned by sparks, but also ensures the flexibility of the movement of the suction arm. A unique rotating structure is designed on the position of the suction hood to ensure that the suction hood can be aligned with the welding position in any orientation, so that the suction arm can effectively capture the smoke and dust generated during the welding process. The advantage of the suction arm capture is that it can be close to the place where the smoke is generated, and the collection effect is better.
3) Room tupe fume extraction system
Room-type dust removal is suitable for the purification of fumes and smoke generated during the production of automated equipment, such as welding robots, welding machines, grinding, grinding and polishing of metal and plastic parts, drilling, thermal processing, cutting and crushing, stone processing, powder packaging, solid particles and various dusts and fumes produced by mixing and processing.
For working conditions such as robot automatic welding, circular seam and longitudinal seam welding, the smoke and dust purifier is installed with the robot workstation, so that the workstation has its own dust removal function. The fume and smoke are effectively collected through equipment components such as pipes and dust hoods. The room-type design prevents the volatilization and diffusion of smoke to keep the air in the workshop clean.
The working conditions with moderate welding workpieces and large amounts of dust and smoke are suitable for room-type treatment solutions. The room type centralized dust dedusting solution is divided into side suction and top suction method dust collecting ways. The appropriate solution can be designed according to the site conditions and treatment goals.
4) Blow suction type fume extraction system
Blow-suction type dust removal solution is a ventilation air flow composed of blown air and inhaled air flow. Therefore, it is a dust removal method that can effectively control the spread of pollution sources. This dust removal method is installing exhaust inlets on two-span center column or single-span side column (wall) and air outlets on the opposite wall column to form a circulating air flow to drive the smoke and dust into the purification machine, consequently performing overall dust removal and purification in the workshop. This system occupies a small area and has obvious purification effect, which is suitable for the purification of smoke and smoke in more complex production workshops.
7. Company information
Jinan Moland Environmental Tech Co., Ltd., is located in No. 11889 Jingshi West Road, Changqing District, Jinan City, Shandong, China, established in 2016. It`s an environmental protection technology enterprise specializing in research, development, manufacture and sale of efficient smoke purification systems.
The company is committed to reducing the environmental impact of production process, protecting workers from harmful gases and dust, and creating a cleaner working environment. At present, the company′s products have been successfully applied in automobile, railway, construction machinery, marine engineering, aviation and other mechanical processing industries, as well as new materials, grain, wood, recycled resources processing and other industries. The company has passed the ISO 9001 quality management system certification, obtained the certification of China Environmental Protection Products issued by China Environmental Protection Industry Association, and CE certification of EU. It also has a number of invention patents, utility model patents and appearance patents. Through continuous R&D and innovation, many products of the company have reached the international leading level.
Moland′s environmental services cover the whole process from project design, product manufacturing to installation, commissioning and after-sales service. We will provide you with the most professional governance program and the best quality service.
Manual Welding Fume Exhaust System,Welding Dust Collector,Cartridge Filter Jinan Moland Environmental Tech Co.,Ltd , https://www.sdmoland.com
H 2 CO 3 H + +HCO 3 - H + +CO 3 2 - (H 2 CO 3 ) H + +HCO 3 - 2H + +CO 3 2 - =1 (A) =K 1 (B) =K 2 (C)