Nickel concentrate reduces magnesium oxide process technology

I. Overview

Jinchuan company beneficiation plant a beneficiation plant ore processing Long's first hybrid designed processing capacity of 1200t / d, have broken mine, mill floating, concentrate transport three processes. Among them, the grinding and floating process uses a three-stage grinding and three-stage flotation stage grinding and selection process. After the series transformation in the late 1980s and early 1990s, the production capacity of 1500t/d was formed. In the late 90's, after continuous tapping and transformation, especially in 2000 and 2001, two consecutive 150t/d capacity expansions have now produced a production capacity of 2000t/d.

At present, the Longshou mixed ore refers to the mixed ore of three different mining areas in the east, middle and west of the Longshou Mine, rather than the mixed ore with a vulcanization rate of 45% to 60% as defined by the ore industry type. Some of the rich mixed ores (including more than 1.3% of Ni) are treated by one beneficiation, and the other part of the leaner ore (containing about 1.12% of Ni) is treated by the second choice grinding and floating workshop.

This article explores the Longshou mixed mine with a Ni grade above 1.30%.

2. Ore properties and main mineral processing characteristics

(1) Main metal minerals and beneficiation process characteristics of Longshou mixed ore

Long first mixed ore mainly purple metallic minerals iron-sulfur nickel ore, pentlandite, pyrite, pyrrhotite, yellow copper ore, copper and other parties; gangue minerals are serpentine, chlorite, Talc and carbonate. The sulphur nickel sulphide is considered to be the most easily floated nickel sulphide mineral. Nickel pyrite is a relatively good choice of nickel minerals, its selection effect is second only to the purple sulphur nickel iron ore, the main reason is that its primary particle size is smaller than that of purple ilmenite, due to the pentlandite in the medium and fine grain ore. The magnetite is closely symbiotic with a network structure, and most of the grinding process cannot be dissociated by the monomer, resulting in a slightly poor floatability of the pentlandite. Oxidation will make the floatability of the sulphur nickel-iron ore worse. Therefore, for nickel sulphide ore mainly composed of sulphur nickel sulphide, fast mining, fast transportation and quick selection are required. The longer the ore is stored, the more difficult it is to sort.

The general serpentine ore is treated with xanthate as a collector . The nickel recovery rate and vulcanization rate are close to or close to each other. It is a relatively good choice of nickel sulfide ore. The use of a modifier can improve the concentrate grade and the recovery rate is not significantly improved. Serpentine has a certain floatability, so the concentrate of about 30% gangue minerals considerable part of the serpentine, resulting in lower grade metal concentrate, high magnesium oxide content. The serpentine content in the strongly altered ore is small, and the sulfide loss is severe in the general flotation production.

Studies have shown that there is no significant difference in the selectivity of nickel-sulphide minerals in various types of factories and mines, but the gangue minerals in the ore have a significant impact on the selection of production. Therefore, in the research work to improve the nickel minerals selection index or reduce the magnesium oxide in the concentrate, Attention must be paid to the inhibition of gangue minerals.

(2) Flotation process properties of magnesium gangue minerals

The main gangue minerals in Jinchuan copper sulfide and nickel deposits are magnesium-containing silicates. Due to geological alteration, these silicates mainly exist in the form of serpentine, chlorite and talc. These gangue minerals are copper, The flotation of nickel has a greater impact.

1. Structure of major gangue minerals

Serpentine is the simplest mineral in layered carbonate minerals. Its structural formula is [Mg ₃ Si ₂ O ₃ (OH)]. It contains a layer of siloxane tetrahedron, brucite in its absence. The layer acquires an extra charge, so it is sandwiched with another silicon tetrahedral hexagonal mesh. Once there is no net charge on the talc layer and only van der Waals force, the interlayer is cracked and the talc is very soft.

Chlorite is also a layered silicate mineral with a structural formula of (Mg·Al·Fe) ₁₂ [(SiAl) ₈ O ₂₂ ](OH ₁₂ ), which is a layer of brucite sandwiched between double-layered mica . Formed, if the brucite layer is destroyed, the mineral splits. It is the softest than the first two minerals.

2. The floatability of gangue minerals

Serpentine is abundant in nickel concentrates and affects the quality of concentrates. In the practice of nickel ore production, it is found that serpentine enters nickel concentrate in large quantities and is difficult to remove. The reason is that serpentine has strong magnetic properties during the formation process, and magnetic serpentine adsorption and the same magnetic sulfide The surface enters the concentrate together; in addition, the positively charged serpentine is easily adsorbed and floated on the surface of the negatively charged nickel mineral.

The chlorite is difficult to float in the nickel mineral flotation. In addition, the chlorite is loose and brittle, and is easily muddy during the grinding process. The behavior of chlorite slime in nickel mineral flotation is basically consistent with that of serpentine fine mud.

Talc has a non-polar surface, good hydrophobicity, and strong natural floatability. It can float well only with a foaming agent. Nickel mineral flotation, talc is easy to enter the concentrate.

Third, the status quo of magnesium reduction

(1) Process flow and its characteristics

In the 1990s, in order to provide low-magnesium qualified concentrates for flash furnaces, to make up for the shortage of rich ore concentrates in the second mining area, Jinchuan Company's concentrator, Jinchuan Nickel- Cobalt Research and Design Institute, Central South University of Technology, Northwest Institute of Mining and Metallurgy, etc. A large number of experimental studies have been carried out on magnesium oxide in Longshou mixed ore low concentrate. These experimental studies are summarized in three types:

1. Reduce magnesium by changing the process flow;

2, through the new agent to achieve the activation of useful minerals, inhibiting the gangue minerals of the agent to reduce magnesium;

3. Reduce magnesium by changing the process flow and adding new agents.

Through a large number of experimental studies, the first selection workshop carried out the process transformation of the 2 ^# system and 1 ^# system in June, 1998, respectively, forming the current magnesium reduction process, and the output of the low-magnesium concentrate to the flash furnace. The new magnesium reduction process is mainly to strengthen the selection of operations, increase the number of rough selection, and achieve the purpose of reducing magnesium by improving the concentrate grade. The on-site production practice proves that the three-stage grinding and three-stage flotation stage grinding process is the successful experience of selecting the Jinchuan Longshou mixed ore, which can effectively recover the useful minerals from sufficient monomer dissociation and reduce over-grinding. And mineral surface contamination. The production practice also proves that the process is more adaptable, which can not only organize magnesium reduction production, but also provide low-magnesium concentrate for the second-stage flash furnace (magnesium content in concentrate is ≤7%); it can also organize low-concentration grade production. , to provide raw materials for the production of the first phase of the furnace, and in both cases, the recovery rate is basically not lost. A selection of grinding process (block diagram) is shown in Figure 1.

Figure 1 Process of grinding and floating principle

(II) Statistical analysis of production indicators

The classification and statistics of the production indicators of the selected factories from January to August in 2000 were drawn from the statistical results.

1. The original ore grade has a direct impact on the indicator. With the increase of the ore grade, the concentrate grade and recovery rate are increasing, and the MgO content in the concentrate is gradually decreasing.

2. When the ore grade of nickel is greater than 1.2%, as long as the grade of nickel in the concentrate is controlled to be greater than 6.5%, the content of MgO in the concentrate can be less than 7%, indicating that under the existing process conditions, a certain concentrate grade is guaranteed to be magnesium. primary condition.

3. When the original ore nickel grade is less than 1.2%, to ensure the MgO content in the concentrate, the concentrate grade must be increased to more than 7%, and the recovery rate is more lost.

Fourth, analysis of magnesium reduction

(1) The effect of ore properties on magnesium reduction

1. The natural floatability of minerals in MgO

Most silicate minerals have strong covalent or ionic bonds, are hydrophilic, and have poor floatability, such as olivine and pyroxene. However, serpentine, talc, chlorite and other minerals are special layered or double-chain silicate minerals. After breaking, the surface bond force is molecular bond force, good hydrophobicity and natural buoyancy, during the flotation process. It is easy to enter the concentrate, resulting in an increase in MgO content in the concentrate. Most of the ore in the Jinchuan mining area has been altered. The original olivine and pyroxene are mostly eroded into serpentine, talc, chlorite, etc. These magnesium-containing minerals have good floatability and are the main reason why MgO is difficult to suppress.

2, ore hardness

The hardness of the ore becomes smaller, and it is easier to be muddy during the grinding process. The alteration of the ore and the development of the structural compression zone in the ore will aggravate this trend, and the serpentine, talc and chlorite minerals are wrapped in the metal. The surface of the mineral enters the concentrate, causing an increase in MgO content.

3. Ore grade

The metal sulfide in the ore is negatively correlated with the magnesium-containing gangue mineral, that is, the lower the ore grade, the higher the MgO content. From January to August 2001, the accumulated Ni ore grade of Longshou mixed ore processed by ore processing was 1.333%, which was 0.017% lower than the planned Ni ore grade of 1.35%, and decreased by 0.112% from 1.445% in the same period of 2000, showing a significant downward trend. Increased the difficulty of magnesium reduction work.

(2) Limitations of the magnesium reduction program

In view of improving the nickel-copper index and reducing the work of MgO in the concentrate, the various universities and research institutes have done a lot of experimental research, and different technical measures for different ores have certain effects, but once Production applications, the effect is obvious. The ore dressing process is very complicated, and industrial production is a continuous process. Because the mine is still unable to achieve ore or stable ore mining, the selected ore properties and grades fluctuate greatly, so that the (or relatively fixed) ore dressing equipment, The process process handles many changes in ore, making process control more complicated, so that some seemingly better technical measures are difficult to achieve the desired results when applied in the field.

V. Research direction of magnesium reduction work

(1) Process mineralogy research

The mineral composition of the Longshou mixed ore in the first mining area is complex. In the past, the mineral technology research focused on the investigation of the ore. The research on the occurrence state and process characteristics of the intermediate products in the ore dressing process is rare, and the magnesium-containing veins are clarified. The trend of the stone minerals in the whole flotation process and the process characteristics of the gangue minerals in the intermediate products during the beneficiation process have important guiding significance for the research of magnesium reduction process and medicaments, and are the key to magnesium reduction.

(II) Research on new process of mineral processing

The research on the magnesium reduction process of the Longshou mixed ore in Jinjin No.1 Mining Area was later than that in the second mining area, but some progress has been made. However, from the perspective of production practice, it is necessary to continue to explore in depth.

Australia's G·D·Senior et al. used a new process to treat nickel-sulfurized ore, which can remove 98% of magnesium-containing minerals. The main points of the process are: pre-flotation of magnesium-containing minerals, and then separate the materials and segmentation inhibition. Containing magnesium minerals, and finally activating nickel-containing minerals, high-grade nickel concentrates are obtained. The main minerals of mixed ore in Jinchuan No.1 Mine are serpentine. Its good floatability is an important reason for the high content of MgO in concentrate. It can be considered to pre-float serpentine and suppress other contents by magnesium-reducing agent. Magnesium minerals to achieve the purpose of reducing magnesium. In addition, G·D·Senior et al. believe that materials with different particle sizes have different floatability and requirements for pharmaceuticals, which is also worth learning.

(3) Research on new flotation reagents

Under the premise of the process determination, the most critical factor affecting the flotation process and final indicators is the rational selection and use of flotation reagents. Due to the interaction between the agents in the flotation process, it is difficult to really understand the mechanism of action of the ore dressing agent. Many existing theories appear in the form of hypotheses and speculations, and it is impossible to definitively describe how the agent acts on minerals. How to change its flotation characteristics hinders the relevance of flotation reagent research. Therefore, in-depth study of the mechanism of action of various agents is an important part of magnesium reduction research.

(4) Attention should be paid to the optimization of the overall indicators

In the past studies on the reduction of MgO in concentrates by Jinchuan ore in various colleges and research institutes, although some attention was paid to the influence of other indicators and certain technical measures were taken, such attention was not enough. Many magnesium reduction programs have to be achieved by increasing the grade of concentrates to varying degrees, and the increase in concentrate grades is bound to result in a loss of recovery. If it is to reduce magnesium, it will greatly improve the concentrate grade, resulting in excessive loss of recovery rate. It is economically unreasonable. Jinchuan resources are limited. When considering magnesium reduction to meet the requirements of flash furnace, it should not lose nickel too much. Copper recovery rate, special attention should be paid to the optimization of the overall index, which should be paid enough attention in the future research of magnesium reduction process.

Conclusion

The magnesium reduction process of Longshou mixed ore in Jinchuan No. 1 Mine has made certain progress through extensive research by universities and research institutes. Some have been used in industrial production. At present, the magnesium reduction process of a beneficiation is fully absorbed. Based on the results of various researches, the production practice also proves that when the ore properties and grades are relatively stable, it is necessary to improve the concentrate grade to achieve the purpose of fresh-keeping; when the ore properties deteriorate, the MgO content in the concentrate cannot be Satisfying the requirements, etc. Therefore, further research is needed to reduce the MgO content in the concentrate in the first mine mixed ore in a mining area.