Long-Luanchuan Molybdenum Co., Ltd. (referred to as Long-company) was developed in 2005 Nannihu and the establishment of a state-owned mining enterprises, under the Henan Province Coal Group Wing. Xiaomiaoling Mineral Processing Company is a branch of Longyu Company. It is mainly engaged in molybdenum selection activities. It was completed and put into operation in October 2008. The production scale is 10 000 tons of molybdenum ore.

Since the Xiaomiaoling mineral processing company was put into operation in October 2008, the copper content in the molybdenum concentrate products has continued to be high (up to 1.15%), and the copper inhibitors have continued to increase in tonnage, which not only seriously affects the production process indicators. And the quality of molybdenum concentrate products also poses a serious challenge to reduce production costs and reduce environmental pollution. To this end, through the data collection, research and analysis of the original process flow of the selected system, the partial transformation of the original process flow of the selected system is targeted and the application practice is carried out.

First, the nature of the ore

Natural type of ore angle quartz rock type, accounting for 63.64% of the total ore, other types skarn, granite and diopside, plagioclase angle rock type. The ore structure is a scaly, flaky, frame-like, bundle-shaped, radial structure with a unique structure of molybdenite. In addition, there are mosaic structures, inclusion structures, self-form-heavy-grain structures, meta-residual structures and meta-annular structures. Ore structure: The fine vein structure is the main structural form of the ore in the Nannihu mining area. In addition, there are dip-like structures and fine vein-disseminated structures.

The main metal minerals molybdenite, pyrite, pyrrhotite and other times chalcopyrite, magnetite, hematite and limonite small amount, sphalerite, galena; major gangue The minerals are garnet , diopside, quartz, plagioclase, followed by calcite , fluorite , wollastonite and a small amount of chlorite, epidote, mica and so on.

Molybdenite is the main molybdenum-bearing mineral in the deposit, which is distributed in various types of rocks, and its content is small and unevenly distributed. The content of skarn type ore is relatively higher than other types of ore, and the average content is 0.1% to 0.2%. The molybdenum deposits in the skarn and the Yunyingyan are often unevenly distributed by dissemination. Molybdenite often aggregates in a single or two or even multiple crystals. It can also be intermittently veined and finely veined. Occasionally, sporadic molybdenum ore is scattered in the outer side of the mineralized vein wall. The molybdenum deposits in the skarn and the Yunyingyan-Yuyingyan are often unevenly distributed by dissemination. Molybdenum ore is mostly self-shaped-semi-automorphic, with scales and flakes, and some of them are aggregated into a frame, bundle, and radial. The particle size is generally small, mostly 0.008 mm × 0.02 mm to 0.02 mm × 0.06 mm, the minimum can reach 0.002 mm to 0.004 mm, a few coarse particles, as large as 0.5 to 25 mm, often in the gangue with a width greater than 10 to 50 cm. Output. The boundary line with the gangue mineral is straight, sometimes in the form of small flakes and inlaid with gangue minerals. Most of its continuum is connected to quartz, and a few are connected to other gangue minerals.

Second, the original selection system process and its production status

The dressing of Xiaomiaoling Concentration Company adopts the process of three-stage crushing, two-stage grinding, one rough selection, three selections and four sweeps. Among them, ball milling, rough selection, and sweeping are dual systems, and the selection and re-grinding are single systems. The ball milling operation consists of two MQY-φ4800mm×7000mm overflow ball mills and two sets of CZ-500×6 hydrocyclones. The slurry enters the molybdenum rough selection after adding the drug, and the rough selection operation adopts four φ4m×10m flotation columns. The overflow enters the selected system, and the underflow enters the molybdenum sweeping operation. The sweeping system consists of 32 BS-KYF39. The composition is a gas-filled agitation flotation machine.

The molybdenum selection system consists of molybdenum polishing, molybdenum selection 1, molybdenum selection 2, molybdenum selection, 3, 4 flotation columns in series, ie molybdenum fine sweeping overflow to molybdenum selection 1, molybdenum selection 1 Overflow to Molybdenum Select 2, Molybdenum Select 2 Overflow to Molybdenum Select 3; Molybdenum Select 3 Underflow to Molybdenum Select 2 Feed, Molybdenum Select 2 Underflow to Molybdenum Select 1 Feed, Molybdenum Select 1 The underflow is used to sweep the molybdenum fine to select the material, and the molybdenum fine sweep bottom is passed through the buffer pool and finally returned to the molybdenum rough selection, as shown in FIG.

Figure 1 Raw molybdenum selection system process

Since the beginning of April-May 2009, the molybdenum selection system has been abnormal. The outstanding performance is that the copper content in the molybdenum-selected 3 overflow products is seriously exceeded (the workshop requires 0.2% to 0.4%), and there is a trend of continuing to rise, and copper. The consumption of inhibitors is increasing, which not only increases the difficulty of operation, but also greatly increases the production cost.

Third, molybdenum selection system process local transformation attempt

Through the sampling and analysis of the various process steps of the molybdenum selection system, and drawing on the advanced experience of absorbing the copper from other molybdenum selection plants, the process of technological transformation is bold. It can be seen from Fig. 1 that the molybdenum fine sweeping bottom stream is not diverted to the sweeping flotation machine, and no open split or partial open split is achieved, so that the molybdenum selection 1, molybdenum selection 2, and molybdenum selection 3 are suppressed. Impurities (such as copper) not only do not discharge the system in time, but also do multiple vicious cycles and enrichment throughout the rough-selection system; 2 there is no “excess” drug cycle that is completely consumed by the molybdenum selection system in the selection system. When rough selection, it will pollute the rough selection of molybdenum and affect the selection index. 3 Most of the bottom flow of molybdenum cleaning should be difficult or difficult to select mineral particles and the content of impurities is large. When it is recycled to molybdenum selection 1, it will be aggravated. The burden of molybdenum selection affects the quality of the molybdenum rough-selection overflow, except that the rough selection of fresh materials by molybdenum masks the difficulty of selecting this part of the material.

The process flow after partial modification of the molybdenum selection system process is shown in Figure 2.

Figure 2 Process after the transformation

It can be seen from Fig. 2 that the molybdenum fine sweeping bottom portion realizes open-circuit splitting, which can timely discharge the useless impurities suppressed in the selected zone to the molybdenum rough-selection system, avoiding multiple vicious cycles of these impurities in the whole system and Enrichment, which can reduce the unnecessary consumption of the medicament, can also achieve the desired effect. Secondly, the “excess” agent that has not been completely consumed by the molybdenum selection system can be timely discharged through the sweeping to the tailings dam, avoiding the secondary pollution of the molybdenum rough-selection overflow, thereby further improving the molybdenum selective flotation. The efficiency also correspondingly reduces the burden of molybdenum rough selection overflow selection.

Fourth, the transformation effect analysis

(1) Analysis of copper reduction effect of molybdenum concentrate

Before and after the local modification of the molybdenum selection system process, the copper content in the molybdenum concentrate is shown in Table 1. In order to compare the differences of copper content in each batch before the partial transformation of the process, the batch after the partial transformation of the process and the batch before and after the process, a one-way analysis of variance was introduced.

Table 1 Statistics of copper content in molybdenum concentrate from April to June

1, the basic principle

Factors provided single factor test as A, a total of _{A 1, A 2, ...,} A r levels, arranged respectively _{n 1, n 2, ...,} n r replicates, wherein the i-th horizontal arrangement of n _i times The experiment was repeated and the resulting samples were X _i1 , X _i2 , . . . , X _in , and the corresponding observations were x _i1 , x _i2 , . . . , x _ini . Where n ₁ +n ₂ +...+n _r =n, and assuming that r normal numbers i = 1, 2, ..., r obey N(μ _i , σ ² ). If μ = 1 / n ∑ _{n i} μ _{i is specified} , the mathematical model of one-way ANOVA is expressed by equation (1):

Where i = 1, 2, ..., r; j = 1, 2, ..., ni; μ is the population mean; α _i = μ _{i -} μ, which is the effect of the level A _i , and n _i α _i =0 Each ε _{ij is} independent of each other and obeys N(0, σ ² ). The null hypothesis H ₀ is each α _i =0.

2, effect analysis

According to the data in Table 1, SAS 8.1 was used for one-way ANOVA to compare the differences between different batches of copper content before and after partial modification of the selected system process. The results of the analysis are shown in Table 2.

Table 2 Variance analysis results

It can be seen from Table 2 that the difference in copper content of each batch is extremely significant (significance level is less than 0.0001), and the difference in copper content of each batch before and after partial modification of the selected system process is also extremely significant. In order to compare the differences of copper content in each batch before and after the local transformation of the process, Fisher's Least Significant Difference (LSD) was used to make multiple comparisons between groups, and the confidence intervals were predicted at 95% confidence level. The results are shown in Table 3. Show.

Table 3 LSD multiple comparison results

Note: *** in the table indicates that the confidence level is 95%.

According to Table 3, the following four points can be obtained.

(1) The copper content of each shift after the partial modification of the molybdenum selection system process process is significantly smaller than the copper content before the local transformation of the molybdenum selection system process. The copper content of the A, B, and C shifts after the transformation and the A, B, and C shifts before the transformation is significant at the 95% confidence level, as shown in Table 3, No. 1 to 3, 6 to 8, 10 to 12 As shown, this fully demonstrates that the attempt to reform the local process of the molybdenum selection system is scientific and reasonable and effective.

(2) After the partial transformation of the molybdenum selection system process, there is no significant difference between the copper contents of the shifts of A, B and C. There is no significant difference in the copper content between Class A and Class B, Class A and Class C, Class B and Class C after the transformation at 95% confidence level, as shown in No. 4 to 5, 9 in Table 3.

(3) There is no significant difference in the copper content between the shifts of A, B and C before the partial modification of the process of molybdenum selection system, as shown in 13 to 15 in the serial number of Table 3. Based on the above, the factor of shift has little effect on copper content, that is to say, it is reasonable in personnel arrangement, or in the era of machine labor, efficiency depends mainly on machines rather than employees.

(4) Part A and Class B, Class A and Class B after partial transformation of the molybdenum selection system process. The confidence intervals for the difference in copper content between Class B and Class B were (-0.0675, 0.0852), (-0.0603, 0.0924), (-0.0692, 0.0836), respectively, and the difference was not significant. This allows the shift difference detection interval (-0.0692, 0.0924) to be extended to control production management.

(II) Analysis of other mineral processing indicators

The main production indicators of the molybdenum selection system before and after the process transformation are shown in Table 4.

Table 4 Comparison of main production indicators before and after process modification %

It can be seen from Table 4 that after the technological transformation of the molybdenum selection system, the theoretical recovery rate and the actual recovery rate are increased by 1% compared with that before the transformation; the tailings grade changes little before and after the transformation, but they are all controlled within the company's requirements (tail The grade of the ore is ≤0. 012 0%).

(3) Inhibitor consumption

1. Before processing the 1t ore, the average consumption of sodium cyanide is about 60g. After the process, the average consumption of sodium cyanide is about 30g, that is, the average tonnage of copper inhibitors after process modification is reduced by half.

2. Sodium cyanide is one of the most traditional and effective inhibitors and one of the most environmentally damaging inhibitors. Recently, Xiaomiaoling Mineral Processing Co., Ltd. is actively researching and exploring the use of sodium thioglycolate instead of sodium cyanide as an effective inhibitor of copper.

V. Benefit evaluation

(1) Set up a daily processing capacity of 10,000 tons of raw ore, 0.1000% of the original ore grade. For every 1 percentage point increase in the actual recovery rate, the daily concentrate can be 45% dry concentrate of about 0.22 t, and the monthly product can be 45%. The dry concentrate is 6.6 t, and the annual concentrate can be 45% dry concentrate 79.2 t; the molybdenum concentrate is calculated at the market price of 2,000 yuan/(t·degree), which can create an additional value of 19,800 yuan per day for the enterprise. The month can create an additional value of 594 000 yuan for the enterprise, which can create an additional value of 7.128 million yuan for the enterprise every year. In the long run, it can create huge economic benefits for the enterprise.

(2) After the technological transformation, the consumption of sodium cyanide is reduced by about 30 g, and the annual processing of ore is 3.3 million tons. The annual consumption of sodium cyanide can be reduced by 99 tons, calculated according to the market price of 19,658 yuan/t. The company saved material costs of 1,942,200 yuan.

(3) The use of sodium cyanide is greatly reduced, environmental pollution is greatly reduced, and ecological benefits are increasingly prominent; while the actual recovery rate is increased, and the social benefits brought about by rare and non-renewable molybdenum resources are also inestimable.

Conclusion

(1) After this transformation, the amount of sodium cyanide is basically maintained at around 300 kg per day, and the copper content is stable at around 0.2%. It can be seen that sodium cyanide can be used at least 300 kg per day. This transformation technically guarantees the smooth production of qualified molybdenum concentrates, and greatly reduces the amount of sodium cyanide inhibitors, effectively reducing environmental pollution, economic, ecological and social benefits.

(2) Through one-way analysis of variance, it is found that under the 95% confidence level, the copper content of the selected system process is significantly less than that before the transformation, between the shifts before the transformation and between the shifts after the transformation. There was no significant difference in copper content. Confidence intervals (-0.0692, 0.0924) can be used as indicators for supervision and management to capture production.

(III) Statistical analysis and production practice prove that the molybdenum fine sweeping underflow process transformation is reasonable, feasible and practical, and therefore has important practical significance.

(4) The success of partial transformation of the molybdenum selection system can create an additional benefit of 7.128 million yuan per year.

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