All-Slime Cyanidation Process for Tanzania 1,200t/d Gold Plant

 The choice of mineral processing process is the key to determining the gold recovery rate and production efficiency of a gold processing plant, especially for the Tanzania 1,200t/d gold project with complex ore properties. The project involves two types of ore—sulfide ore with a high gold grade of 10.7g/t and oxide ore with a relatively low grade of 2.4g/t, and gold is the only valuable element. To efficiently recover gold from these two types of ore, Xinhai’s technical team经过 in-depth analysis of ore properties and a large number of experimental verifications, finally determined to adopt the all-slime cyanidation gold extraction process, which achieved excellent leaching effects—93.75% for sulfide ore and 91.58% for oxide ore, setting a high standard for gold recovery in the local area.

All-slime cyanidation is a mature and efficient gold extraction process, which is mainly suitable for processing fine-grained disseminated gold ore, oxide gold ore and sulfide gold ore after oxidation roasting. Its core principle is to fully dissociate gold particles from gangue minerals through fine grinding, and then use cyanide solution to leach gold, so as to realize the separation of gold from ore. For the Tanzania project, the all-slime cyanidation process is particularly suitable because of the fine embedded particle size of gold in both sulfide and oxide ores, which requires sufficient dissociation through grinding to ensure the leaching effect.

The reason why Xinhai chose the all-slime cyanidation process for the Tanzania project is not only based on the ore properties, but also considering the project’s production scale and economic benefits. Compared with other gold extraction processes such as gravity concentration-cyanidation combined process, the all-slime cyanidation process has the advantages of simple process flow, high gold recovery rate, stable operation and low production cost, which is very suitable for large-scale production of 1,200t/d. At the same time, the process can effectively handle both sulfide and oxide ores, avoiding the need to set up two sets of independent processing systems, which greatly reduces the project’s investment and operation cost.

To ensure the leaching effect of the all-slime cyanidation process, Xinhai made targeted optimizations in the key links of the process. First of all, in the grinding stage, a closed-circuit grinding and cyclone classification process was adopted to ensure that the ore is ground to the required particle size, so that the gold particles are fully dissociated. The particle size of the grinding product directly affects the leaching rate—if the particle size is too coarse, the gold particles cannot be fully contacted with the cyanide solution, resulting in low leaching rate; if the particle size is too fine, it will increase the viscosity of the pulp, affect the leaching efficiency and increase the energy consumption. Xinhai’s technical team determined the optimal grinding particle size through a large number of experiments, balancing the leaching effect and energy consumption.

Secondly, in the cyanidation leaching stage, Xinhai optimized the leaching parameters such as cyanide concentration, leaching time, pulp pH value and aeration rate. For sulfide ore with high gold grade, the leaching time was properly extended and the cyanide concentration was adjusted to ensure that the gold is fully leached; for oxide ore with low grade but easy leaching, the leaching parameters were optimized to improve the leaching efficiency and reduce the consumption of cyanide. At the same time, Xinhai adopted advanced leaching equipment to ensure the uniform mixing of pulp and cyanide solution, and improve the contact efficiency between gold particles and leaching agent.

The application of the all-slime cyanidation process in the Tanzania 1,200t/d gold project has achieved remarkable results. The leaching rate of sulfide ore reached 93.75% and that of oxide ore reached 91.58%, which are higher than the average level of the same type of gold projects. This not only ensures the full utilization of gold resources, but also brings considerable economic benefits to the customer. In addition, the all-slime cyanidation process adopted by Xinhai has good environmental protection performance—through the effective treatment of cyanide-containing wastewater and tailings, the environmental pollution caused by the production process is minimized, which meets Tanzania’s strict environmental protection requirements.

The successful application of the all-slime cyanidation process in the Tanzania project fully demonstrates Xinhai’s strong technical strength and ability to customize solutions according to ore properties. This process not only provides a reliable technical guarantee for the project’s stable operation and high efficiency, but also provides a valuable reference for the processing of similar gold ores in East Africa. In the future, Xinhai will continue to carry out technological innovation, optimize mineral processing processes, and provide more efficient and environmentally friendly technical solutions for global mining customers.

Tanzania 1,200t/d Gold Mineral Processing Plant: Xinhai’s EPC+M+O Success and Technological Innovation

 Tanzania, a country rich in gold resources in East Africa, has become a key market for global mining investment with its abundant mineral reserves and improving investment environment. Against this backdrop, Xinhai Mining, a leading provider of mineral processing complete solutions, successfully undertook the Tanzania 1,200t/d gold mineral processing plant project, an integrated EPC+M+O project that integrates Engineering, Procurement, Construction, Mining Management and Operation. This project, with its unique ore properties and high production scale, has become a benchmark for efficient and sustainable gold mining in Tanzania, demonstrating Xinhai’s strong comprehensive strength in the global mining service field.

The Tanzania 1,200t/d gold project is distinctive in its ore composition: it consists of sulfide ore with a gold grade of 10.7g/t and oxide ore with a gold grade of 2.4g/t, with gold as the only valuable element. This ore characteristics put forward special requirements for the mineral processing process—how to efficiently recover gold from two types of ore with very different grades and properties, while ensuring the stability of production capacity and economic benefits, has become the core challenge of the project. Xinhai, relying on its years of experience in gold mineral processing and rich overseas project practice, customized a targeted overall solution for the project, and the EPC+M+O service mode adopted in the project has laid a solid foundation for the smooth implementation and long-term operation of the project.

The EPC+M+O mode adopted in this project is an advanced service mode in the current large-scale mineral processing plant construction, which solves the pain points of customers in coordinating multiple links such as design, construction and operation. For the Tanzania project, Xinhai took full responsibility for the whole process from the initial project research, process design, equipment procurement and manufacturing, on-site construction and installation, to the later equipment commissioning, trial operation, operation management and technical support. This integrated service mode not only reduces the communication cost and project risk for customers, but also ensures the consistency and efficiency of the whole project process, enabling the project to be put into production on schedule and achieve expected benefits.

In the early stage of the project, Xinhai’s professional technical team conducted in-depth on-site investigations in Tanzania, fully understanding the local natural environment, transportation conditions, industrial supporting facilities and relevant mining policies and regulations. Tanzania has strict requirements on environmental protection and production safety in the mining industry, and Xinhai integrated environmental protection and safety concepts into every link of project design and construction. In view of the local water and electricity resources and labor conditions, Xinhai optimized the process design and equipment configuration to adapt to the local actual situation, reducing the project’s operation cost and improving the adaptability of the plant.

In the process of project implementation, Xinhai adhered to the principles of high quality, high efficiency and safety, and strictly controlled every link. The professional construction team and installation team sent by Xinhai have rich overseas project experience, and strictly constructed and installed in accordance with the design drawings and international standards, ensuring the construction quality. At the same time, Xinhai established a special project management team to track the project progress in real time, coordinate the cooperation between various teams, and solve the problems encountered in the construction process in a timely manner, ensuring the smooth progress of the project.

After the completion of the project, Xinhai continued to provide operation management and technical support services. The professional operation management team formulated scientific operation plans, optimized process parameters, and ensured the stable operation of the plant. The technical support team provided regular technical training and on-site guidance for the local operation personnel, helping them master the operation skills of equipment and process, and realizing the independent operation and management of the plant by the customer. Up to now, the Tanzania 1,200t/d gold processing plant has been operating stably, with the leaching rate of sulfide ore and oxide ore reaching 93.75% and 91.58% respectively, which has been highly recognized by the customer.

This project is not only a successful practice of Xinhai’s EPC+M+O mode in East Africa, but also a positive contribution to the development of Tanzania’s mining industry. It has introduced advanced mineral processing technology and management experience to Tanzania, promoted the technological progress of the local mining industry, created a large number of local employment opportunities, and driven the development of related industries. In the future, Xinhai will continue to uphold the concept of technological innovation and sustainable development, and provide more high-quality mineral processing solutions for global mining customers, helping more mining projects achieve efficient and green development.

Selection and Combination of Siderite Beneficiation Processes – Maximizing Resource Value

 Siderite beneficiation is a complex system engineering, and the selection of beneficiation processes is not fixed—it needs to be determined according to the specific characteristics of the ore, including particle size distribution, chemical composition, mineral intergrowth relationship, impurity content, and other factors. As mentioned earlier, the four core beneficiation processes (flotation, gravity separation, magnetic separation, magnetization roasting-weak magnetic separation) each have their own advantages and limitations. In practical industrial production, a single beneficiation process is often difficult to meet the requirements of high concentrate grade and high recovery rate. Therefore, the combination of multiple processes has become the mainstream trend of siderite beneficiation, which can give full play to the advantages of each process and maximize the utilization value of siderite resources.

First, let’s clarify the selection criteria of a single beneficiation process. For coarse-grained siderite ores (particle size 5-50mm) with simple composition and low impurity content, gravity separation (heavy-media separation or jigging separation) is the preferred method—it has large production capacity, low cost, and can effectively discard gangue. For fine-grained disseminated siderite ores (particle size less than 1mm) with complex intergrowth with gangue, flotation is more suitable—it can achieve effective separation of fine particles and improve the concentrate grade. For siderite ores with associated strong magnetic minerals (such as magnetite), magnetic separation (weak magnetic separation + strong magnetic separation) can be adopted to recover strong magnetic minerals first and then separate siderite. For difficult-to-beneficiate siderite ores (fine particle size, high impurity content, close intergrowth), the magnetization roasting-weak magnetic separation process is the most effective choice, which can fundamentally solve the problem of low separation efficiency.

On the basis of single process selection, the combination of multiple processes can further improve the beneficiation effect. The common combined processes for siderite include: gravity separation + flotation, magnetic separation + flotation, magnetization roasting-weak magnetic separation + flotation, etc. For example, in the processing of coarse to medium-grained siderite ores with fine-grained impurities, the "gravity separation + flotation" combined process is often adopted: first, gravity separation is used to recover coarse-grained siderite concentrate, and the tailings or intermediate products of gravity separation (which contain fine-grained siderite) are sent to flotation for re-selection, so as to improve the overall iron recovery rate and concentrate grade. Another example is the "magnetization roasting-weak magnetic separation + flotation" combined process for difficult-to-beneficiate siderite: after magnetization roasting and weak magnetic separation, the obtained concentrate may still contain a small amount of fine-grained gangue, which can be further purified by flotation to obtain high-grade iron concentrate (iron grade above 65%), meeting the requirements of the steel industry.

In addition to the selection and combination of processes, the optimization of process parameters is also crucial to improving beneficiation efficiency. For example, in the flotation process, the optimization of pulp pH, reagent dosage, and flotation time can significantly improve the separation effect; in the magnetization roasting process, the control of roasting temperature, reducing agent dosage, and roasting time directly affects the transformation rate of siderite to magnetite; in the gravity separation process, the adjustment of separation medium specific gravity and water flow velocity can improve the separation accuracy.

In conclusion, the selection and combination of siderite beneficiation processes must be based on detailed ore characterization and experimental research, and the principle of "adapting to ore properties, optimizing process flow, reducing cost, and protecting the environment" must be adhered to. With the continuous development of mineral processing technology, new processes and equipment (such as high-efficiency flotation reagents, advanced magnetic separation equipment, and energy-saving roasting technology) are constantly emerging, which will further promote the efficient utilization of siderite resources and provide strong support for the sustainable development of the steel industry.

Siderite Magnetization Roasting-Weak Magnetic Separation Process – Solving the Difficulty of Beneficiation

 For siderite ores with complex compositions, fine particle size, and close intergrowth with gangue minerals, single beneficiation processes (such as flotation, gravity separation, or magnetic separation) often struggle to obtain high-grade iron concentrates. At this time, the magnetization roasting-weak magnetic separation process becomes the most effective solution. This process combines roasting and magnetic separation, transforming siderite into a strong magnetic mineral through roasting, thereby realizing efficient separation with conventional weak magnetic separation equipment. It is known as the "key technology" for difficult-to-beneficiate siderite and has been widely promoted and applied in industrial production.

The core of the magnetization roasting-weak magnetic separation process is the magnetization roasting step, whose principle is to heat siderite in a reducing atmosphere (using coal, coke, natural gas, or other reducing agents) to decompose the carbonate in the ore and transform siderite into magnetite (Fe₃O₄), a strong magnetic mineral. The chemical reaction equation is: 3FeCO₃ + C → Fe₃O₄ + 3CO₂↑ + CO↑. During the roasting process, two key changes occur: first, the carbon dioxide in siderite is decomposed and discharged, which increases the iron content of the ore (theoretical iron content of magnetite is 72.4%, which is much higher than that of siderite); second, the magnetic susceptibility of iron minerals is significantly enhanced—magnetite is a strong magnetic mineral, whose magnetic susceptibility is dozens of times higher than that of siderite, making it easy to be separated by weak magnetic separation. At the same time, the magnetic properties of gangue minerals (such as quartz, calcite) remain basically unchanged, which further improves the separation effect.

The magnetization roasting process is mainly divided into three types: shaft furnace roasting, rotary kiln roasting, and fluidized bed roasting. Among them, rotary kiln roasting is the most widely used in siderite beneficiation due to its stable roasting effect, large processing capacity, and strong adaptability to ore particle size. The rotary kiln is a long cylindrical equipment that rotates continuously; the ore and reducing agent are fed into the kiln from one end, and heated to 550-700℃ (the optimal roasting temperature for siderite) by a burner at the other end. Under the action of high temperature and reducing atmosphere, siderite is gradually transformed into magnetite. After roasting, the ore (called roasted ore) is cooled to the appropriate temperature and then sent to the next process.

The roasted ore is sent to a weak magnetic separator for separation. Due to the strong magnetic properties of magnetite, it is easily adsorbed by the magnetic field of the weak magnetic separator and separated from non-magnetic gangue to form high-grade iron concentrate. The weak magnetic separation equipment used is mainly a drum magnetic separator, which has the advantages of simple structure, high processing efficiency, and low energy consumption. Compared with strong magnetic separation, weak magnetic separation has lower equipment investment and operation cost, which greatly reduces the overall cost of the beneficiation process.

The magnetization roasting-weak magnetic separation process has the advantages of high iron concentrate grade, high recovery rate, and strong adaptability to difficult-to-beneficiate siderite ores. However, it also has certain limitations: the roasting process requires a large amount of energy and reducing agents, which increases the production cost; at the same time, the roasting process will generate flue gas, which needs to be treated to meet environmental protection standards. Therefore, in industrial design, it is necessary to comprehensively consider the ore properties, economic benefits, and environmental protection requirements to optimize the process parameters.

Siderite Magnetic Separation Process – Leveraging Magnetic Properties for Efficient Separation

 As a weak magnetic mineral, siderite has a low magnetic susceptibility, which means it cannot be effectively separated by conventional weak magnetic separation equipment (such as drum magnetic separators) used for magnetite. However, with the development of magnetic separation technology, strong magnetic separation has become a feasible and efficient method for siderite beneficiation. The core principle of siderite magnetic separation is to use the difference in magnetic susceptibility between siderite and gangue minerals: under the action of a strong magnetic field, weak magnetic siderite particles are attracted by the magnetic field and separated from non-magnetic gangue minerals, achieving the purpose of beneficiation. This process is especially suitable for siderite ores with low impurity content and relatively coarse particle size, and it can also be used as a pre-separation or re-separation process in combination with other methods.

The main equipment of the siderite strong magnetic separation process is the wet strong magnetic separator, which is divided into vertical ring strong magnetic separators, horizontal belt strong magnetic separators, and high-gradient strong magnetic separators according to their structure and working principle. Among them, the vertical ring wet strong magnetic separator is the most widely used in siderite beneficiation. It has a high magnetic field intensity (up to 1.2-2.0T), strong processing capacity, and good separation effect. The equipment works in a wet state: the ore pulp is fed into the magnetic separation chamber, and under the action of the strong magnetic field generated by the magnetic system, siderite particles are adsorbed on the surface of the magnetic medium (such as magnetic rods, magnetic plates) and moved to the concentrate discharge port with the rotation of the magnetic system, while gangue minerals that are not adsorbed are discharged as tailings along with the pulp.

To further improve the iron concentrate grade and iron recovery rate, a combined process of "weak magnetic separation first, then strong magnetic separation" is often adopted in industrial production. The specific process is as follows: first, the raw ore is crushed and ground to the required particle size, and then sent to a weak magnetic separator. Although siderite is a weak magnetic mineral, some iron-bearing minerals (such as associated magnetite) in the ore can be recovered by weak magnetic separation, forming a primary concentrate. The tailings from weak magnetic separation, which are mainly composed of siderite and gangue, are then sent to a strong magnetic separator for re-selection: the strong magnetic field adsorbs siderite particles, discards most of the gangue tailings, and the obtained concentrate is combined with the primary concentrate from weak magnetic separation to form the final iron concentrate. This combined process not only improves the recovery rate of iron but also reduces the processing load of the strong magnetic separator, saving energy and reducing costs.

The advantages of the siderite magnetic separation process are obvious: it has a simple process flow, high separation efficiency, low environmental pollution (no need for a large number of chemical reagents), and strong adaptability to ore properties. However, it also has certain limitations: the magnetic field intensity has high requirements, the equipment investment cost is relatively high, and it is not suitable for fine-grained disseminated siderite ores (the separation effect is poor when the particle size is less than 0.1mm). Therefore, the selection of magnetic separation process needs to be based on the detailed analysis of ore properties and economic benefits.