Nylon shocking fine screen

The nylon slamming vibrating screen is a fine-grain screening device successfully developed in the mid-1970s. It has achieved good results by using it to improve the grade of magnetically selected iron concentrate. After the use of magnetic separation plant promotion, China's magnetic separation iron concentrate grade has reached the world's advanced level.
The structure of the nylon vibrating screen is shown in the figure below.


The figure above shows a 400×1200mm self-flowing ore fine sieve for testing. It can be seen from the above figure that the fine sieve structure is simple, mainly composed of a feeder, a sieve surface, a sieve frame, a sieve body and a striking device. The upper part is a feeder, and the lower part is a sieve body welded by steel plates, which is provided with a screen frame and a screen surface, and a tapping device is arranged behind the screen frame. The feeder is composed of a buffer tank and a homogenizer. The buffer is controlled by a valve to maintain the constant pressure inside the tank and adjust the amount of ore. The slurry flows to the homogenizer and flows evenly through the screen surface and is divided into two products, the sieve and the sieve. The sieve surface is a sieve with a long hole and is made of a fixed sieve or sieve. The arrangement of the screen bars is perpendicular to the direction of the material. The screen surface is mounted on the screen frame, and the screen frame is suspended by the spring on the screen body, and the screen body and the horizontal support are inclined, and can be adjusted. There is a striking plate on the back of the screen frame, and the striking hammer of the striking device periodically strikes the plate to cause instantaneous vibration of the screen surface to prevent the screen hole from being clogged. The tapping mechanism (below) is controlled by a DC motor and a cam machine to adjust the tap height and number of times. Industrial test A fine screen uses a single motor to drive 15 beaters in series.


The striking device has been improved, and the improved striking device is shown below.


2. Technical performance
The technical characteristics of the 400×1200mm nylon shock-absorbing fine sieve are:
Screen size (length × width) 400 × 1200mm
Sieve angle
One section of 55 degrees, two sections of 60 degrees, mesh size 0.2mm
Dimensions First paragraph (15)
(length × width × height) 8.5 × 2.5 × 2.3 m
Second paragraph (12 links)
Separation size 200 mesh Under the sieve -200 mesh content is about 95% Processing capacity 5~8t/set•h
Feed concentration 35~45%
The yield under the sieve is about 50%. The weight of the hammer is 200~250mm.
Number of beats 6 to 21 times / min
Motor power 2.8kW (DC adjustable)
Application example
The fine sieving is mostly used in the fine sifting and regrinding process. The first is the application in the fine sieving and re-grinding process, and the first is applied in the fine sieving and separate regrind process. In order to fully exploit the secondary grinding ability, the previous process 1 is often used when the return amount on the fine sieve is not more than 30%. For the case where the processing of the inlaid cloth is fine, and the second-stage grinding load is originally large, In order to improve the concentrate grade, the latter process is used.
Before the fine screening application, the Nanfen Iron Ore Selection Plant used a single wet weak magnetic field magnetic separation process. After the fine sieving is applied, it becomes a magnetic separation and fine screening combined process of fine screening and re-grinding. (The following figure). [next]

The following table shows the comparison of production indicators before and after fine screening in the three-choice workshop. From the 32-month production index from 1976 to 1978, it can be seen that the concentrate grade is increasing year by year, the mill capacity is decreasing year by year, the average concentrate grade is increased by 1%, and the mill capacity is reduced by 3~5t/set•h. After the fine screening was put into production, this situation was changed. From the 21 months of 1980 in 1980 to the 32 months before the start of production, the concentrate grade increased by 2.61% and the ore processing capacity increased by 2.69t/set•h under the conditions of similar magnetic properties and ore grades; In 1979, compared with 1977 before the production, its magnetic rate, ore grade, and tailings were almost equal, while the iron concentrate grade was increased by 2.48%, and the mill capacity was increased by 5.41 t/set•h. It can be seen that the application of fine screening has achieved significant effects in improving the grade and yield of iron concentrate. The 18-month production statistics after the second-selection workshop was put into production, the concentrate grade was 2.719% higher than before the production, and the mill capacity was increased by 15t/set•h. [next]

  Changes in main indicators after fine screening and production in the three-choice workshop

item   Head

single   Bit

Pre-cast production

After put into production







January to August

9 to 2 months

January to May

Magnetic rate








Raw ore grade








Concentrate grade








Tailings grade








Recovery rate (theory)








Taiwan time ability

1/ set· h







The fine screening of the Dashihe plant is used to treat the magnetic concentrate of the second-stage fine-ground magnetic separation. The equipment connection diagram is shown in the figure below.


The results of the two process comparisons obtained from the production review are listed in the table below. The fluctuations in grades are shown in the figure below.

   Comparison of two process production indicators

flow    Cheng

Raw ore processing capacity

Secondary grading overflow particle size

Comprehensive production index TFe,%


-150 mesh, %

Raw ore



Application fine screen






No fine screening







As can be seen from the above chart, the fine iron content of the concentrate using the fine screening process is as high as 66.19%, the probability of occurrence of grade 65-68% is 86.67%, and that of the less than 64% is only 1.49%. The iron content of the concentrate is high and stable, mainly because the fine sieve can ensure that the final selected particle size of the undersize product is steadily maintained at -150 mesh and accounts for 90-95%. The concentrate iron content without the fine screening process averages only 64.31%, and fluctuates within a large range of 62-67% iron, and even 8.33% of the concentrate contains less than 62%. From the change of the secondary cyclone graded overflow particle size (-150 mesh) without the fine screening process, it is known that the -150 mesh content fluctuates greatly within the range of 50-90%, which indicates the rotation without the fine screening process. The flow device failed to ensure the final inclusion of the particle size, resulting in a low grade of concentrate and a large change.
The results of further testing of the fine screening process are: Dashihe iron ore continues to finely grind to below -200 mesh, and it is possible to obtain concentrates containing 67 to 68% of iron. The cumulative grade of -100 mesh in the fine mesh concentrate is similar to that of the fine mesh, but the difference in the yield of the two +100 meshes affects the iron content of the concentrate, and the fine mesh is +100 mesh. The yield was 4.41%, the grade was reduced, 0.68%, the yield of +100 mesh without fine screening was 14.14%, and the grade was decreased by 3.34%. It is one of the main advantages of reducing the coarse particles and losing the biomass into the concentrate.
Fine sieving is a secondary control grading operation in the process. It can strictly control the final selected particle size stability and greatly reduce the coarse particles in the concentrate, thus ensuring the stable quality of the final concentrate.
The application of fine sieve improves the secondary grinding efficiency, so that the new grade (-150 mesh or -200 mesh) produced per cubic meter of volume per second mill increases from 0.7-0.8t to 1.0-1.1t. Increase by 25 to 40%.
During the period from 1977 to 1980, more than 20 selected factories promoted the application of fine screening, with more than 2,000 units, and achieved the following effects.
(1) Applied in magnetite, roasting magnetite and hematite-magnetite ore, the concentrate grade can generally be increased by 1 to 6%.
(2) The selection of the water plant can stabilize the concentrate grade, and the fluctuation range is reduced from ±3% to ±0.5%. It can also save the workload of the mixing field, such as flipping and mixing, so that it can be directly into the sintering machine.
(3) Dashihe, water plant, Nanfen, Chengchao, Wuxi, Liangshan and other iron ore dressing plants, while increasing the concentrate grade, increasing the capacity of the ball mill , or when the concentrate grade is the same, the ball mill The ability to increase the time is 10 to 15%. Some factories have improved the grinding efficiency of the second stage mill by about 25-40%.
(4) The economic benefits of the plant were greatly improved. According to the statistics of Shougang Mining Company, the total profit of 1979 was 16 times higher than that of 1975. Many small and medium-sized factories have turned losses into profits.

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