CN102228866B - Compound classification method and equipment for ground ore product - Google Patents

Abstract

The invention relates to a method and equipment for compound classification of ore grinding products, belonging to the technical field of mineral processing. Combining vibratory screening with spiral classification method, the grinding products are vibratingly screened through the double-layer chute vibrating screen to obtain the on-screen material and the under-screen material, and then the on-screen material is directly sent to the spiral classifier for classification. The material is returned to the grinding machine for regrinding, and the fine material overflows from both sides of the classification box and is combined with the material under the screen to be sent to the subsequent sorting operation. The chute vibrating screening machine is located on the side of the spiral classifier, and the tail end of the ore discharge chute is directly connected to the ore feeding port on the spiral classifier box body. The box body in the classifying area of the spiral classifier is higher than the conventional box body height. It has the advantages of greatly reducing the anti-enrichment of fine-grained heavy minerals in sand settling or returning sand, closed-circuit grinding over-grinding and sand settling with less fineness, high classification efficiency, and direct closed-circuit with the grinding machine. For the transformation of existing grinding and grading equipment, a new screening spiral compound classifier can also be manufactured to be used in conjunction with the grinding machine.

Description

Composite grading method and equipment for grinding ore products

technical field

The invention relates to a rapid and high-efficiency composite classification method and equipment for coarse and fine particles of ore grinding products, belonging to the technical field of mineral processing.

Background technique

Grinding is an important process link in a concentrator, and the particle size distribution of the grinding product has a great influence on the subsequent sorting operations. The product discharged from the grinding is in the form of pulp with a wide range of particle sizes. Generally, it cannot directly enter the sorting operation. It needs supporting grading equipment to classify the coarse and fine particles. The coarse particle returns to the grinding machine for grinding, and the fine particle enters the subsequent secondary mill. The ore is re-grinded or directly entered into the sorting operation. At present, there are mainly three kinds of grading equipment supporting the grinding machine, one is a spiral classifier, the other is a cyclone, and the other is a screening machine. The spiral classifier is the traditional classifying equipment that has been used for the longest time. It relies on the classifying area at the discharge end to carry out gravity sedimentation classifying. Its outstanding advantages are stable and reliable operation, convenient operation and maintenance, and the returning sand is automatically lifted and returned to the grinding machine to form a closed-circuit grinding , no other auxiliary equipment is required. The biggest disadvantage of the spiral classifier is that the overflow is easy to run rough, and the sand return is serious, which leads to low classification efficiency of the equipment, and the classification quality efficiency is generally only 20-40%. At the same time, fine-grained heavy minerals sink into the sand and return to the mill and easily form over-crushing, which affects the subsequent sorting indicators. Due to the above-mentioned defects of the spiral classifier, it has been gradually replaced by the cyclone in large-scale concentrators in recent years. The cyclone relies on the centrifugal force field generated by the high-speed rotation of the pulp and the gravity field with poor particle density and particle size for classification. Its outstanding advantages are high classification efficiency, and the classification efficiency can reach 60-70%. In addition, the equipment is small in size and easy to configure. There are also several obvious disadvantages in the cyclone. First, the energy consumption is high, and the slurry must be fed in by a pump or a high-level slurry tank; The operation is inconvenient, and the slag must be pre-screened for the slurry, otherwise the coarse ore or broken steel balls will cause the blockage of the grit chamber and make it difficult to clean. At the same time, the classification principle of the cyclone cannot avoid the anti-enrichment phenomenon of the grit, that is, the heavy mineral particles enter the grit preferentially, and it is easy to cause over-crushing after returning to the mill for regrinding, which is not good for the subsequent separation. The sieving machine can also be used as a supporting grading equipment for the grinding machine. Its biggest advantage is that the material is classified according to the geometric size of the sieve hole, and the fine-grained heavy minerals pass through the sieve first, which can effectively avoid spiral classifiers and cyclones. The return enrichment phenomenon of heavy minerals can reduce the over-crushing phenomenon of the grinding machine, and the graded products are beneficial to the subsequent separation. The high-frequency vibration of the screening machine can also obtain high screening efficiency, and the screening mass efficiency can reach more than 70%. However, when the screening machine and the grinding machine are used alone, the grinding slurry must be lifted by a pump, and the energy consumption is high. In addition, the processing capacity of the grinding machines in medium and large concentrators is relatively large, which cannot be handled by a single screening machine, and it is difficult to configure multiple screening machines. Thirdly, the screens of the screening machines are easy to block and wear seriously under heavy load. , It is difficult to maintain a stable screening effect, so the application of closed-circuit grinding of screening machines and grinding machines is seldom.

In order to improve the classification efficiency of the spiral classifier, a lot of work has been carried out at home and abroad. Some have transformed the spiral classifier into a multi-stage conical classifier to produce multiple overflow products (new spiral classifier, ZL96241462.X), and some have added inclined plates in the classifying area to increase the classifying area to avoid overflow and thickening (inclined plate Spiral classifier, ZL98245016.8), and some cylinder screens are added at the end of the spiral sand return to improve the screening efficiency (composite circular screen spiral classifier, ZL99230913.1). These improvement measures have a certain effect in improving the efficiency of the spiral classifier, but in view of some problems in the structure and operation stability of the equipment, the above equipment has not been widely popularized and applied.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, provide a compound classification method and device for grinding ore products, integrate the chute vibrating screen and double-side discharge stirring type spiral classification method and device, and control the overflow discharge of the spiral classifier High, composite grading of grinding products to reduce anti-enrichment of fine-grained heavy minerals.

The compound grading method for ore grinding products of the present invention is: combine the vibration screening method and the spiral grading method to carry out compound grading on the ore grinding products; The sieve surface is soaked in the spiral grading overflow liquid, and the grinding products are vibratingly screened through the double-layer vibrating screen to obtain the on-screen material and the under-screen material mixed in the spiral grading overflow liquid, and then the on-screen material is directly sent to Enter the spiral classifier for spiral classification, so that the coarse sand settles to the bottom and is transported to the ore end of the grinding machine through the spiral blades, and flows into the grinding machine for regrinding. At the same time, the fine-grained materials are stirred and redispersed from the classification The overflow on both sides of the box is discharged, combined with the under-screen material and sent to the subsequent sorting operation. The overflow ore pulp classified by the spiral classifier is collected through the horizontal overflow ore discharge pipes on both sides of the spiral classifier classification area box and the overflow collection tank below it, and then combined with the under-screen material and sent into the For subsequent sorting operations, the classifying area of the spiral classifier used is 300-600mm higher than that of ordinary spiral classifiers (selected in the service provided according to actual needs) to ensure the particle size of the overflow pulp.

The equipment used in the compound classification method for grinding products of the present invention is: it is made up of a chute vibrating screening machine and a spiral classifier, the chute vibrating screening machine is at the side of the spiral classifying machine, and the tail end of its ore discharge chute 11 is directly connected to The ore feeding port on the casing 12 of the spiral classifier. The chute vibrating screening machine includes a screen box support 3 and a screen box 2 installed on it, a screen frame 4 supported on the screen box by springs, a vibrator 5 installed on the top of the screen frame, and an upper layer coarse screen installed in the middle and lower part of the screen frame. The screen 7 and the lower fine screen 8, the under-screen material collection box installed at the lower part of the screen box 9, the under-screen ore discharge pipe and flow control valve installed at the bottom of the collection box, and the ore feed chute installed at the front of the screen frame 1. And the ore discharge chute 11 installed at the end of the screen frame and directly connected to the ore inlet of the spiral classifier. The screen frame 4, the ore feed chute 1 and the ore discharge chute 11 are connected and sealed by flexible materials such as rubber. The sieve aperture of the coarse screen is 1-10mm, and the sieve aperture of the fine screen is 0.1-0.5mm. The sieve plate or screen made of polyurethane, wear-resistant rubber or stainless steel is used, and the upper and lower screens are tensioned. Finally, it is fastened on the screen frame with beading, bolts, screws, etc., and the vibration frequency of the vibrator is 960-3000 times per minute (selected in the given service according to actual needs).

The spiral classifier is an ordinary double-side discharge stirring type spiral classifier. The height of the box in the classifying area is 300-600mm higher than that of the conventional spiral classifier (selected in the given service according to actual needs), and the classifying area is close to the chute vibrating screener. 2 to 5 circles (selected according to actual needs) at the end of the ore discharge chute are equipped with (welded or screwed) 2 to 10 stirring blades 15 (the number is determined according to actual needs) on the spiral blade 14, and the box body 12 is close to the vibrating screen. Two to five overflow discharge pipes 16 with a diameter of 20 to 80 mm (quantity and size are determined according to actual needs) are installed (welded or screwed) on both sides of the mine end, and the bottom of the overflow discharge pipe is installed (welded or screwed). Fixed) overflow collection tank 17 with a slope of 5-10% (determined according to actual needs). The stirring blade 15 on the spiral blade 14 can improve the classification efficiency of the spiral classifier, so that the fine-grained material that sinks at the bottom is in a suspended state after being stirred, and is discharged through the ore discharge pipes arranged on both sides in the shortest path. After the lower products are combined, they enter the follow-up operation as a graded overflow.

When working, the grinding products are discharged into the upper screen 7 of the vibrating screen frame 2 of the chute through the chute 1. Under the vibration of the vibrator 5, the screen frame 2 makes an approximate linear motion, and the large ore and coarse-grained debris It becomes the above-sieve product of the upper sieve 7, and the under-sieve product of the upper sieve 7 is further screened in the lower sieve 8, and the sieve surface of the lower sieve 8 is immersed in the pulp as a whole, so the screening of the lower sieve 8 belongs to submerged sieving. Under the action of the vibrator 5, the material on the screen is fully loosened after being thrown forward and upward, and the fine-grained material, especially the fine-grained material of heavy minerals, quickly passes through the screen under the action of gravity and fluid drag and becomes the under-screen material. Under the action of the screening machine, most fine-grained qualified products have been discharged through the under-screen material collection box 9 and the discharge pipe. The coarse-grained materials on the sieve and the fine-grained materials that have not been sieved are discharged into the box 12 of the spiral classifier through the ore discharge chute 11, and are further classified by gravity settlement (secondary classification). The spiral blade 14 is conveyed to the ore feeding end of the ore grinding machine, and flows into the ore grinding machine for regrinding. During the rotation of the spiral blade 14, under the action of the stirring blade 15, part of the fine-grained material mixed in the coarse-grained material is stirred and re-dispersed, and is discharged from the overflow on both sides of the classification box under the action of the rising liquid flow. The pipe 16 is discharged through the shortest path and merged into the overflow collection tank 17, and the product under the screen of the sieving machine and the overflow product of the classifier are combined as the ore feed for subsequent operations. Since the screening machine is integrally connected with the spiral classifier, the liquid level in the screening machine is adjusted by the position of the overflow pipe 16 of the classifier and the material control valve 10 under the screen, so as to ensure that the screening of the lower layer of the screening machine is carried out under the liquid. The vibration of the net makes the pulp form a strong vibration wave, forming a continuous automatic cleaning of the screen, reducing and avoiding the blockage and wear of the screen, and the ore discharge channel set in the underscreen collection box generates suction for the pulp, The fine-grained grade can pass through the screen quickly, so as to ensure the high screening efficiency of the chute vibrating screen. Through the integration of the chute vibrating screen and the double-side discharge stirring spiral classifier, the classification method of grinding products is innovated, the purpose of composite classification is achieved, and the anti-enrichment phenomenon of fine-grained heavy minerals is reduced.

The present invention adopts compound classification method and corresponding equipment, can realize following positive effect:

(1) Using the pre-screening of the chute vibrating screen, most of the fine-grained grades of the grinding products, especially the fine-grained heavy minerals, are separated in time, which greatly reduces the gravity and centrifugal sedimentation separation of traditional spiral classifiers and cyclones The ubiquitous anti-enrichment phenomenon of fine-grained heavy minerals in sand settling or returning sand can reduce over-grinding in closed-circuit grinding and provide better graded products for subsequent sorting operations;

(2) Using the stirring blades installed on the spiral blades of the spiral classifier, the gravity sedimentation classification process of the spiral classifier is strengthened, and the fine-grained grades mixed in the coarse-grained grades are re-separated, thereby reducing the inclusion of fine-grained particles in the sand settling , greatly improving the classification efficiency;

(3) Use the position of the overflow discharge pipes on both sides of the classifier to control the classification liquid level. First, it can reduce the coarseness of the overflow. Second, it can control the overflow liquid level above the lower screen of the sieving machine, so that The fine sieve is carried out under the liquid surface, thereby forming an automatic cleaning of the sieve surface, greatly reducing the blockage and wear of the sieve, and ensuring the sieving machine to obtain high and stable screening efficiency;

(4) By using the method and equipment of the present invention to carry out compound classification on the grinding products, the classification efficiency of the overall equipment can reach more than 70%, the anti-enrichment of sand settling can be reduced by more than 70%, and the over-grinding rate of the grinding machine can be reduced by more than 30% , the processing capacity of the grinding machine is increased by more than 20%, and the recovery rate of subsequent sorting operations is increased by 2-5 percentage points;

(5) The advantages of the spiral classifier have been fully utilized, and the direct closed circuit with the grinding machine can be realized, without the need for lifting equipment such as sand pumps to lift the pulp;

(6) The method and equipment can be used not only for the transformation of the existing grinding system classification equipment, but also for the production of new screening spiral compound classifiers for use in conjunction with the grinding machine.

Description of drawings

Fig. 1 is the schematic diagram of the front view of the compound classification device of the present invention;

Fig. 2 is a schematic side view of the compound classification device of the present invention;

Fig. 3 is a schematic top view of the compound classification device of the present invention.

In the figure, 1-discharging chute and feeding chute, 2-screen box of chute vibrating screen, 3-support of vibrating screen; 4-screen frame of vibrating screen, 5-exciter of vibrating screen, 6-vibrating screen Frame support spring, 7-upper sieve plate of vibrating sieve, 8-lower screen of vibrating sieve, 9-material collection box under vibrating sieve, 10-material discharge pipe and control valve under vibrating sieve, 11-vibrating sieve Material discharge chute on the screen, 12-box of the spiral classifier, 13-drive shaft of the spiral classifier, 14-spiral blade of the spiral classifier, 15-stirring blade of the spiral classifier, 16-overflow of the spiral classifier Discharge pipe, overflow collection tank for 17-spiral classifier.

Detailed ways

The content of the present invention will be further elaborated below in conjunction with the accompanying drawings and embodiments, but the content of the present invention is not limited to the stated scope.

Example 1: A tin ore concentrator that processes 120 tons of ore a day uses a ￠1200 single-screw classifier and a ￠1500×3000 grinding machine for closed-circuit grinding and grading, and the grinding fineness is -200 mesh, accounting for 75%. The measured mass efficiency of the spiral classifier based on 0.074mm is 38%, and the over-crushing rate (-10μm) of the classification overflow is 32%. The subsequent sorting operation indicators are not ideal. The grading system is retrofitted with the method and apparatus of the present invention.

The compound classification method for grinding products is: combine the vibratory screening method with the spiral classification method to carry out compound classification for the grinding products. The sieve surface is soaked in the spiral grading overflow liquid, and the grinding products are vibratingly screened through the double-layer vibrating screen to obtain the on-screen material and the under-screen material mixed in the spiral grading overflow liquid, and then the on-screen material is directly sent to Enter the spiral classifier for spiral classification, so that the coarse sand settles to the bottom and is transported to the ore end of the grinding machine through the spiral blades, and flows into the grinding machine for regrinding. At the same time, the fine-grained materials are stirred and redispersed from the classification The overflow on both sides of the box is discharged, combined with the under-screen material and sent to the subsequent sorting operation. The overflow ore pulp classified by the spiral classifier is collected through the horizontal overflow ore discharge pipes on both sides of the spiral classifier classification area box and the overflow collection tank below it, and then combined with the under-screen material and sent into the For subsequent sorting operations, the classifying area of the spiral classifier used is 400mm higher than that of ordinary spiral classifiers to ensure the particle size of the overflow pulp.

The equipment used is composed of a chute vibrating screening machine and a spiral classifier. The chute vibrating screening machine is located on the side of the spiral classifier, and the tail end of the ore discharge chute is directly connected to the ore feeding port on the spiral classifier box. That is, the angle of the original classifier is increased to 15 ^° , and the outward translation is 800mm, and the chute vibrating screen device of the present invention is added between the grinding machine and the classifier. The chute vibratory screening device includes a screen box support 3 and a screen box 2 installed on it, a screen frame 4 supported on the screen box by springs, a vibrator 5 installed on the top of the screen frame, and an upper layer installed in the middle and lower part of the screen frame. Coarse screen 7 and lower fine screen 8, under-screen material collection box 9 installed at the bottom of the screen box, under-screen ore discharge pipe and flow control valve 10 installed at the bottom of the collection box, ore feeder installed at the front of the screen frame The chute 1 and the ore discharge chute 11 installed at the tail of the screen frame and directly connected to the ore inlet of the spiral classifier, the screen frame 4, the ore feed chute 1 and the ore discharge chute 11 are connected and sealed by rubber materials. The length, width and height of the vibrating screen are 800×600×800mm. The upper sieve adopts a polyurethane sieve plate with an aperture of 1mm, and the lower sieve adopts a wear-resistant stainless steel screen with an aperture of 0.1mm. The bead and screw are fastened on the screen frame, and the vibration frequency of the vibrator is 3000 times/min.

The spiral classifier is an ordinary double-side discharge stirring spiral classifier. The height of the box in the classification area is 400mm higher than that of the conventional spiral classifier. Four stirring blades 15 with a length, width and thickness of 120×60×12mm are welded on the top, and three overflow discharge pipes 16 with a diameter of 40mm are welded on both sides of the box body 12 near the ore discharge end of the vibrating screen machine. The bottom of the pipe is welded with an overflow collection tank 17 with a width of 150mm and a slope of 8%. The stirring blade 15 on the spiral blade 14 can improve the classification efficiency of the spiral classifier, so that the fine-grained materials that sink at the bottom are stirred and suspended, and then discharged in the shortest path through the ore discharge pipes arranged on both sides. After the lower products are combined, they enter the follow-up operation as a graded overflow.

After the grading system was transformed by the method and equipment of the present invention, 3 months of continuous operation assessment and index test were carried out. The grading quality efficiency of the equipment according to 0.074mm grading reached 63%, and the particles less than 10um in the overflow Grade content is reduced from 32% to 19%, and the over-grinding rate is reduced by 41%. After the classification efficiency is improved, the processing capacity of the grinding machine is increased by 25%, and the daily processing capacity of the concentrator reaches 150t/d. After the overflow crushing rate is reduced, the tin recovery rate of the sorting operation is increased by 3.8 percentage points.

Example 2: In a copper ore concentrator that processes 1,500 tons of ore a day, a ￠2000 double-screw classifier and a ￠2700×3600 ore grinding machine are used for closed-circuit grinding and grading in the first-stage grinding operation, and the ore discharge granularity is 0.3mm , the grinding fineness is -200 mesh, accounting for 60%, the measured mass efficiency of the spiral classifier according to 0.3mm classification is 50%, the classification mass efficiency calculated according to 0.074mm is 32%, and the over-grinding rate of classification overflow (-10μm ) is 26%.

The grading system is transformed with the method and equipment of the present invention, and the method and device used are the same as those in Example 1. That is, the angle of the original classifier is increased to 15 ⁰ , and the outward translation is 1000mm, and the chute vibrating screen of the present invention is added between the grinding machine and the classifying machine. The length, width and height of the vibrating screen are 1200×800×1000mm, The upper sieve of the vibrating screen adopts a polyurethane sieve plate with an aperture of 5mm, and the lower layer adopts a wear-resistant stainless steel screen with an aperture of 0.35mm. The vibration frequency is 1480 times/min. The ore discharge chute of the material on the vibrating screen is directly connected to the feeding port of the spiral classifier. The height of the box in the classifying area of the spiral classifier is 600mm, and five screws with a diameter of 20mm are fixed on both sides of the box along the horizontal direction. The overflow ore discharge pipe, under which the overflow collection tank with a width of 200mm and a slope of 10% is fixed with screws. Fix 10 stirring blades whose length, width and thickness are 180×80×16 mm with screws on each of the 2 turns of the helical blade in the classification area. The material under the screen of the vibrating screen and the overflow of the classifier are merged into the second stage of grinding, and the sand returned by the classifier is automatically lifted and returned to the mill for regrinding.

After the modification of the grading system by the method and equipment of the present invention, 3 months of continuous operation assessment and index test were carried out. The grading quality and efficiency calculated by 0.3mm of the equipment reached 73%, and the grading quality and efficiency calculated by 0.074mm It reached 68%, the content of particle size less than 10um in the overflow was reduced from 26% to 18%, and the over-grinding rate was reduced by 31%. After the classification efficiency is improved, the processing capacity of the grinding machine is increased by 20%, and the daily processing capacity of the concentrator reaches 1800t/d. After the overflow crushing rate is reduced, the copper recovery rate of the sorting operation is increased by 2.6 percentage points.

Example 3: In an iron ore concentrator that processes 1,000 tons of ore a day, the SLFS1500 screening spiral compound classifier of the present invention and the ￠2100×3000 ore grinding machine are used in the first-stage grinding operation to perform closed-circuit grinding and grading. It is 0.4mm, and the grinding fineness is -200 mesh and accounts for 55%. The specific method and device are the same as in Example 1.

The length, width and height of the chute vibrating screen of the screening spiral compound classifier are 1000×750×900mm. The upper sieve of the vibrating screen adopts a polyurethane sieve plate with an aperture of 6mm, and the lower layer adopts a wear-resistant stainless steel screen with an aperture of 0.45mm. The vibration frequency of the vibrator is 1480 times/min. The ore discharge chute of the vibrating screen and the feeding port of the spiral classifier are flexibly connected by rubber material. The spiral classifier is a ￠1500 double helix, and the box in the classifying area is 400mm higher than the conventional spiral classifier. Four overflow ore discharge pipes with a diameter of 50mm are welded on both sides of the box along the horizontal direction. 200mm, 8% slope overflow collection tank. Weld 6 stirring blades with a length, width and thickness of 150×60×14mm on each of the 3 turns of the helical blade at the ore discharge end of the classification area. The material under the screen of the vibrating screen and the overflow of the classifier are merged into the second stage of grinding, and the sand returned by the classifier is automatically lifted and returned to the mill for regrinding.

After the transformation of the classification system by the method and equipment of the present invention is completed, through 3 months of continuous operation assessment and index test, the classification quality efficiency of the screening screw classifier calculated by 0.4mm reaches 75%, and the efficiency calculated by 0.074mm The classification efficiency has reached 71%, and the content of particle fractions smaller than 10um in the under-sieve and overflow products is 16%, which has reached the expected use effect.

Example 4: In a copper ore dressing plant, a ￠2000 double-helix classifier and a ￠2700×3600 grinding machine are used for closed-circuit grinding and grading in the first-stage grinding operation. The ore discharge particle size is 0.3mm, and the grinding fineness is - 200 mesh accounts for 60%, the measured mass efficiency of the spiral classifier according to 0.3mm classification is 50%, the classification mass efficiency calculated according to 0.074mm is 32%, and the over-grinding rate (-10μm) of the classification overflow is 26%. The grading method and device are the same as in Example 1.

The length, width and height of the chute vibrating screen of the screening spiral compound classifier are 1000×750×900mm. The upper layer of the vibrating screen adopts a wear-resistant rubber plate mesh with an aperture of 10mm, and the lower layer adopts a wear-resistant polyurethane screen with an aperture of 0.5mm. The vibration frequency of the vibrator is 960 times/min. The ore discharge chute of the vibrating screen and the feeding port of the spiral classifier are flexibly connected by rubber material. The spiral classifier is a ￠1500 double helix, and the box in the classifying area is 300mm higher than the conventional spiral classifier. Two overflow ore discharge pipes with a diameter of 80mm are welded on both sides of the box along the horizontal direction. 200mm overflow collection tank with a slope of 5%. Weld two stirring blades with a length, width and thickness of 150×60×14 mm on each of the 4 helical blades at the ore discharge end of the classification area. The material under the screen of the vibrating screen and the overflow of the classifier are merged into the second stage of grinding, and the sand returned by the classifier is automatically lifted and returned to the mill for regrinding.

Claims (7)

1. A compound classification method for ore grinding products, characterized in that: the vibration screening method is combined with the spiral classification method to carry out compound classification for the ore grinding products, firstly a double-layer chute vibration is set in the ore discharge chute area of the ore grinding machine sieve, soak the lower sieve surface in the spiral grading overflow liquid, vibrate and sieve the grinding product through a double-layer vibrating screen, and obtain the material on the sieve and the material under the sieve mixed in the overflow liquid of the spiral grading, and then sieve The upper material is directly sent to the spiral classifier for spiral classification, so that the coarse sand settles to the bottom and is transported to the ore end of the grinding machine through the spiral blade, and then enters the grinding machine by gravity and then grinds. At the same time, the fine-grained material is stirred again After dispersion, it will overflow and discharge from both sides of the grading box, combine with the under-screen material and send it to the subsequent sorting operation. 2. The compound classification method for grinding products according to claim 1, characterized in that: through the horizontal overflow ore discharge pipes on both sides of the casing of the spiral classifier classification area and the overflow collection tank below it, the The overflow of the spiral classification is collected, then combined with the under-screen material, and then sent to the subsequent sorting operation. The classification area box of the spiral classifier used is 300-600mm higher than that of the ordinary spiral classifier. 3. A kind of grinding product composite classification equipment for implementing the grinding product composite classification method of claim 1, is characterized in that: it is made up of chute vibratory screening machine and spiral classifier, and chute vibratory screening machine is in the screw classifier In the side position, the tail end of the ore discharge chute (11) is directly connected to the ore feeding port on the spiral classifier casing (12), and the height of the casing in the classifying area of the spiral classifier is higher than that of a conventional spiral classifier. 4. According to claim 3, the compound grading equipment for grinding ore products for implementing the method for compound grading of ore grinding products according to claim 1 is characterized in that: the chute vibrating screening machine is composed of a screen box bracket (3) and mounted on it The screen box (2), the screen frame (4) supported by springs on the screen box, the vibrator (5) installed on the top of the screen frame, the upper coarse screen (7) installed in the middle and lower part of the screen frame and the lower fine screen The screen (8), the under-screen material collection box (9) installed at the bottom of the screen box, the under-screen ore discharge pipe and flow control valve (10) installed at the bottom of the collection box, and the ore feed chute installed at the front of the screen frame (1), and the ore discharge chute (11) installed at the end of the screen frame and directly connected to the ore mouth of the spiral classifier. The spiral blade (14) in the classification area at the tail end of the ore discharge chute is equipped with a plurality of stirring blades (15), and the two sides of the box (12) near the ore discharge end are respectively equipped with overflow discharge pipes (16), overflow discharge The lower part of the pipe is equipped with an overflow collection tank (17), and the screen frame (4) is connected and sealed with the ore chute (1) and the ore discharge chute (11) by flexible materials. 5. The compound grading equipment for grinding ore products for implementing the method for compound grading of ore grinding products according to claim 1, characterized in that: the height of the box in the classification area of the spiral classifier is higher than that of a conventional spiral classifier 300-600mm high. 6. The compound grading equipment for grinding products for implementing the compound grading method for grinding products according to claim 1, characterized in that: the sieve aperture of the coarse screen is 1-10mm, and the sieve of the fine screen is The aperture of the sieve is 0.1-0.5 mm, and the vibration frequency of the vibrator is 960-3000 times per minute. 7. The compound grading equipment for grinding products for implementing the method for compound grading of ore grinding products according to claim 1, characterized in that: the helical blades equipped with stirring blades are close to the classification area at the tail end of the ore discharge chute 2 to 5 spiral blades, the number of stirring blades installed on each spiral blade is 2 to 10, the number of overflow discharge pipes (16) installed on each side of the box (12) is 2 to 5, the diameter 20-80mm, and the slope of the overflow collection tank (17) is 5-10%.

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