CN108788165A - A method of control low-apparent-density iron powder apparent density - Google Patents

Abstract

The invention discloses a kind of method of control low-apparent-density iron powder apparent density, qualification pushes away boat stove muffin and transports to broken feed bin after being stirred brokenly in feed bin through traveling crane, delivers into nitrogen circulation mechanical crusher and be crushed；Adjust the frequency adjustment grinding rate and adjustment fine powder discrepancy amount of the anti-blocking pipe blower of nitrogen circulation mechanical crusher feed end, each broken powder is classified by the grader for being set to discharge hole of crusher, the thicker powder of granularity, which continues to stay in crusher chamber, to be crushed, the thinner powder of granularity to the heavy collection of cyclone separator；Screenings apparent density is detected after the completion of broken every time, screening, is contrasted with technological requirement, occurs to adjust each frequency conversion parameter in time when deviation.Present invention aims to overcome that nitrogen circulation mechanical crusher low output, of high cost, the difficulty of apparent density control at present, overall process, it is comprehensive control the new process of apparent density during PRODUCTION OF IRON POWDER, can efficiently and accurately control iron powder apparent density.

Description

A method for controlling the bulk density of iron powder with low bulk density

technical field

The invention relates to a process method for adjusting and controlling the bulk density of powder, in particular to a method for controlling the bulk density of iron powder with low bulk density.

Background technique

Powder metallurgy is a new high-tech industry in my country in the 1960s. After entering the 21st century, the powder industry has developed rapidly and the technical level has been continuously improved. Ultrafine iron powder is one of the basic raw materials of powder metallurgy industry. Due to its large specific surface area and activity, it has special properties such as electricity, magnetism, light, catalysis, adsorption and chemical reaction, and is widely used. The bulk density of iron powder with low bulk ratio is generally required to be between 0.8-1.6g/cm3, and the control span is relatively large. Our current control method adopts the fixed speed process of nitrogen circulation mechanical pulverizer, which has low output, high noise, low yield, and process performance indicators such as bulk density are difficult to accurately adjust and control. At present, the means of controlling the loose ratio in this industry are generally achieved by different crushing methods or by changing the crushing speed, which cannot achieve the purpose of precise control.

With the continuous improvement of the technical level and product structure of many product manufacturers, the requirements for process performance indicators such as bulk density are becoming more and more stringent. The method of using a nitrogen circulation mechanical pulverizer to control the bulk density with a fixed speed process has seriously restricted the low bulk density. The development of powder industry. Therefore, it has become an urgent need for the powder metallurgy powder industry to study a new process of replacing the nitrogen circulation mechanical pulverizer with a fixed speed to control the bulk density of the micro-nano powder, to achieve precise control of process performance indicators such as bulk density, to improve work efficiency and reduce production costs. solved problem.

Contents of the invention

In order to solve the above problems, the technical solution provided by the present invention is: a method for controlling the bulk density of iron powder with low bulk density, comprising the following steps;

(a) Feed flow rate: the qualified push boat furnace powder cake is transported to the crushing silo by driving and crushed in the silo, and the powder with a particle size of 10-15mm is transported by nitrogen into the nitrogen circulation mechanical pulverizer for crushing;

(b) Three-stage frequency conversion control: adjust the frequency of the anti-blocking pipe fan at the feeding end of the nitrogen circulation mechanical pulverizer to realize feed volume control, adjust the speed of the nitrogen circulation mechanical pulverizer to realize grinding speed adjustment and adjust the frequency of the classifier to realize fine powder Through the organic coordination of the three process parameters, the adjustment of the input and output volume can achieve the precise control of the high and low bulk density index parameters in the range of 0.8 ~ 1.6g/cm3;

(c) Discharge: The powder after each crushing is classified by the classifier installed at the discharge port of the crusher, the powder with coarser particle size remains in the crushing chamber for crushing, and the powder with finer particle size is classified The fan is sent to the cyclone separator for sedimentation, and then discharged through the outlet of the cyclone dust collector into the ton bag and screened by the ultrasonic vibrating screen;

(d) Process monitoring: After each crushing and screening, the bulk density of the under-screen material is detected, compared with the process requirements, and the frequency conversion parameters are adjusted in time when deviations occur.

As an improvement, the crushing motor is Y2-200L2-2 37KW, and the anti-blocking pipe feeder is ZGFE-2L type.

As an improvement, the adjustment range of the anti-blocking pipe feeder is 0-30HZ.

As an improvement, the model of the bag filter is HL--100 pulse bag filter, and the air volume of the bag filter is 2040m3/h.

As an improvement, the bulk density of the powder at the outlet of the trap should be <0.05.

The technical advantages provided by the present invention are: the purpose of the present invention is to overcome the low output, high cost and difficulty of bulk density control of current nitrogen circulation mechanical pulverizers, and provide a method that utilizes a frequency converter (three-stage frequency conversion method: feed flow rate, rotor speed) , graded speed) as a control means, the new process of controlling the bulk density of iron powder in the whole process and all-round way can effectively and accurately control the bulk density of iron powder. It overcomes the disadvantages that the original equipment only controls part of the influencing factors, cannot achieve all-round and whole-process control, and has inaccurate control results.

The control principle of the present invention shows that in order to increase the bulk density after crushing, the crushing force and crushing time must be increased. The second is to minimize and compress the gaps between the branches. On the contrary, if you want to reduce the bulk density after crushing, you need to reduce the crushing force. First, try to protect the dendritic shape of the powder, keep the branch-like parts in all directions intact, and make the particles loose between particles; The space between remains intact and is not compressed. Therefore, the method of controlling the bulk density of iron powder with low bulk density based on the above principles can be used to control the bulk density in an all-round way. The following is the main content of controlling the three-stage frequency conversion:

1. Feeding flow rate: install an anti-blocking fan between the feeding bin and the crusher inlet, and use a frequency converter to control the speed of the fan to achieve the purpose of controlling the amount of feeding. After the material enters the crushing cavity, the unit force acceleration of the powder changes with the amount of material. According to the F=ma formula, when subjected to the same external force, the mass is inversely proportional to the acceleration. That is to say, according to this process, the greater the feed control frequency, the greater the feed quality, and the smaller the material acceleration, which can be further understood as the smaller crushing force and lower bulk density, on the contrary, it can increase the bulk density.

2. Crusher speed: Install a frequency converter on the main circuit of the crusher motor to control the speed of the crusher, mainly to control the impact force of the powder. According to the F=ma formula, when the material quality is constant, the acceleration is proportional to the impact force. The speed of the crusher is controlled by frequency conversion, so as to control the force of the material and change the bulk density of the material.

3. Classification speed: A classification impeller is installed on the outlet pipeline of the crusher, and the crushing time of the material in the crushing cavity is controlled by controlling the speed of the classification impeller. The greater the classification speed, the greater the resistance to the passage of the material, resulting in the longer the crushing time of the material in the crushing cavity, the greater the deformation of the material, and the branches of the original material particles are squeezed or cut off, so that the volume of the powder is relatively smaller , the bulk density increases; on the contrary, the smaller the grading speed, the smaller the bulk density.

Detailed ways

A method for controlling the bulk density of iron powder with low bulk density, comprising the following steps;

(a) Feed flow rate: the qualified push boat furnace powder cake is transported to the crushing silo by driving and crushed in the silo, and the powder with a particle size of 10-15mm is transported by nitrogen into the nitrogen circulation mechanical pulverizer for crushing;

(b) Three-stage frequency conversion control: adjust the frequency of the anti-blocking pipe fan at the feeding end of the nitrogen circulation mechanical pulverizer to realize feed volume control, adjust the speed of the nitrogen circulation mechanical pulverizer to realize grinding speed adjustment and adjust the frequency of the classifier to realize fine powder Through the organic coordination of the three process parameters, the adjustment of the input and output volume can achieve the purpose of precise control of the high and low bulk density index parameters in the range of 0.8-1.6g/cm3. The actual parameters of the three-stage frequency conversion are tested repeatedly by using the method of orthogonal test. The following three optimal control methods are mainly used in daily production:

serial number Bulk density requirements (g/cm3) Feed frequency conversion (Hz) Broken frequency conversion (Hz) Grading frequency conversion (Hz) 1 0.8-1.0 15-20 23-28 10-12 2 1.0-1.2 10-15 28-33 12-14 3 1.2-1.6 5-10 33-38 14-16

(c) Discharge: The powder after each crushing is classified by the classifier installed at the discharge port of the crusher, the powder with coarser particle size remains in the crushing chamber for crushing, and the powder with finer particle size is classified The fan is sent to the cyclone separator for sedimentation, and then discharged through the outlet of the cyclone dust collector into the ton bag and screened by the ultrasonic vibrating screen;

(d) Process monitoring: After each crushing and screening, the bulk density of the under-screen material is detected, compared with the process requirements, and the frequency conversion parameters are adjusted in time when deviations occur.

The crushing motor is Y2-200L2-2 37KW, and the anti-blocking pipe feeder is ZGFE-2L type.

The adjustment range of the anti-blocking pipe feeder is 0-30HZ.

The bag filter model is HL--100 pulse bag filter, and the air volume of the bag filter is 2040m3/h.

Example 1

The production of 0.8-0.9 low bulk density micro-nano powder is produced by the following steps:

1. Feed flow rate: The qualified push boat furnace powder cake is transported to the crushing silo by driving and crushed into a powder with a particle size of 10-15mm, which is sent to the crusher by the anti-blocking tube feeder for crushing and grinding. The adjustment range of the anti-blocking pipe feeder is 0-30HZ.

2. Equipment parameters: The crusher adopts nitrogen circulation mechanical crushing classifier, the crushing motor is Y ₂ -200L2-237KW; the anti-blocking pipe feeder is ZGFE-2L type, and the feeding capacity is >300kg/h; Roots blower motor Y3 -180L-4 22KW; HL--100 pulse bag dust collector has a processing air volume of 2040m ³ /h, and the suction volume is controlled by a DN100 manual butterfly valve.

3. Parameter control: Open the nitrogen valve to start the Roots blower and crusher. Adjust the speed of the crusher to 25HZ, open the anti-blocking pipe, adjust the speed of the feeder to 15HZ, and adjust the speed of the classifier to 10HZ. After crushing, take the material from the unloading valve to test the bulk density, and take samples for analysis after each crushing for 30 minutes. Bulk density, the average bulk density is 0.85g/cm ³ .

4. Discharge: The pulverized powder moves to the classification area with the upward airflow under the suction of the fan. Under the action of the centrifugal force generated by the adjustable-speed rotating classification turbine, the coarse and fine materials are separated, and the coarse particles descend to the pulverization area to continue pulverization. , the fine particles that meet the particle size requirements enter the cyclone collector through the grading turbine, and the material of the collector is alternately opened and closed by the discharge valve and falls into the big bag.

5. Screening: The under-screen material that meets the particle size requirements enters the storage ton bag to wait for batching, and the over-screen material that does not meet the particle size requirements is sent to the crusher for re-crushing. 6. Process monitoring: Detect the bulk density of the material powder at the outlet of the trap every half hour, compare it with the process requirements, and adjust it in time when the deviation is >0.05, so as to achieve the same bulk density of micro-nano powder in batches.

When adjusting the parameters, it should be noted that when the powder cake appears soft and spongy, the speed of the crusher is adjusted to 25HZ, the speed of the feeder is adjusted to 15HZ when the anti-blocking pipe is opened, and when the classifier is adjusted to 10HZ, the bulk density of the micro-nano powder reaches 0.85g/cm3.

The micro-nano powder with low bulk density produced by this production method, after testing, the bulk density index all meets the standard requirements, and the powder yield rate is increased by 5%.

Example 2

The production of 1.0-1.1 low bulk density micro-nano powder is produced by the following steps:

1. Feed material: Qualified push boat furnace powder cake is hoisted by driving to the crushing silo and crushed in the silo into powder with a particle size of 10-15mm. The adjustment range of plugging feeder is 0～30HZ.

2. Equipment parameters: The crusher adopts nitrogen circulation mechanical crushing classifier, the crushing motor is Y ₂ -200L2-237KW; the anti-blocking pipe feeder is ZGFE-2L type, and the feeding capacity is >300kg/h; Roots blower motor Y3 -180L-4 22KW; HL--100 pulse bag dust collector has a processing air volume of 2040m ³ /h, and the suction volume is controlled by a DN100 manual butterfly valve.

3. Parameter control: Open the nitrogen valve to start the Roots blower and crusher. Adjust the speed of the crusher to 30HZ, open the anti-blocking pipe, adjust the speed of the feeder to 10HZ, and adjust the speed of the classifier to 13HZ. After crushing, take the material from the discharge valve to test the bulk density, and take samples for analysis after each crushing for 30 minutes. Bulk density until it reaches the required range of 1.0-1.1 loose packing.

4. Discharge: The pulverized powder moves to the classification area with the upward airflow under the suction of the fan. Under the action of the centrifugal force generated by the adjustable-speed rotating classification turbine, the coarse and fine materials are separated, and the coarse particles descend to the pulverization area to continue pulverization. , the fine particles that meet the particle size requirements enter the cyclone collector through the grading turbine, and the material of the collector is alternately opened and closed by the discharge valve and falls into the big bag.

5. Screening: The under-screen material that meets the particle size requirements enters the storage ton bag to wait for batching, and the over-screen material that does not meet the particle size requirements is sent to the crusher for re-crushing.

6. Process monitoring: Detect the bulk density of the material powder at the outlet of the trap every half hour, compare it with the process requirements, and adjust it in time when the deviation is >0.05, so as to achieve the same bulk density of micro-nano powder in batches.

When adjusting the parameters, it should be noted that when the powder cake appears soft and sponge-like, the crusher speed is adjusted to 30HZ, the anti-blocking pipe is opened, the feeder speed is adjusted to 10HZ, and the classifier is adjusted to 13HZ, the bulk density of the micro-nano powder will decrease. It can reach 1.1g/cm ³ .

The micro-nano powder with low bulk density produced by this production method, after testing, the bulk density index all meets the standard requirements, and the powder yield rate is increased by 5%.

Example 3

The production of 1.1-1.2 low bulk density micro-nano powder is produced by the following steps:

1. Feed material: Qualified push boat furnace powder cake is hoisted by driving to the crushing silo and crushed in the silo into powder with a particle size of 10-15mm. The adjustment range of plugging feeder is 0～30HZ.

2. Equipment parameters: The crusher adopts nitrogen circulation mechanical crushing classifier, the crushing motor is Y ₂ -200L2-237KW; the anti-blocking pipe feeder is ZGFE-2L type, and the feeding capacity is >300kg/h; Roots blower motor Y3 -180L-4 22KW; HL--100 pulse bag dust collector has a processing air volume of 2040m ³ /h, and the suction volume is controlled by a DN100 manual butterfly valve.

3. Parameter control: Open the nitrogen valve to start the Roots blower and crusher. Adjust the speed of the crusher to 35HZ, open the anti-blocking pipe, adjust the speed of the feeder to 8HZ, and adjust the speed of the classifier to 15HZ. After crushing, take the material from the discharge valve to test the bulk density, and take samples for analysis after each crushing for 30 minutes. Bulk packing density until it reaches the required range of 1.1-1.2 loose packing.

4. Discharge: The pulverized powder moves to the classification area with the upward airflow under the suction of the fan. Under the action of the centrifugal force generated by the adjustable-speed rotating classification turbine, the coarse and fine materials are separated, and the coarse particles descend to the pulverization area to continue pulverization. , the fine particles that meet the particle size requirements enter the cyclone collector through the grading turbine, and the material of the collector is alternately opened and closed by the discharge valve and falls into the big bag.

5. Screening: The under-screen material that meets the particle size requirements enters the storage ton bag to wait for batching, and the over-screen material that does not meet the particle size requirements is sent to the crusher for re-crushing.

6. Process monitoring: Detect the bulk density of the material powder at the outlet of the trap every half hour, compare it with the process requirements, and adjust it in time when the deviation is >0.05, so as to achieve the same bulk density of micro-nano powder in batches.

When adjusting the parameters, it should be noted that when the powder cake is soft like a sponge, the speed of the crusher is adjusted to 35HZ, the speed of the anti-blocking pipe feeder is adjusted to 8HZ, and the classifier is adjusted to 15HZ, the bulk density of the micro-nano powder can be achieved It reaches 1.38g/cm ³ .

The micro-nano powder with low bulk density produced by this production method, after testing, the bulk density index all meets the standard requirements, and the powder yield rate is increased by 5%.

The bulk deviation density of the powder at the outlet of the trap should be <0.05.

The present invention and its embodiments have been described above, but this description is not limiting, and the actual structure is not limited thereto. All in all, if a person of ordinary skill in the art is inspired by it, and without departing from the inventive concept of the present invention, without creatively designing a structure and an embodiment similar to the technical solution, it shall fall within the scope of protection of the present invention.

Claims (5)

1. A method for controlling the bulk density of iron powder with low bulk density, characterized in that: comprise the following steps; (a) Feed flow rate: the qualified push boat furnace powder cake is transported to the crushing silo by driving and crushed in the silo, and the powder with a particle size of 10-15mm is transported by nitrogen into the nitrogen circulation mechanical pulverizer for crushing; (b) Three-stage frequency conversion control: adjust the frequency of the anti-blocking pipe fan at the feeding end of the nitrogen circulation mechanical pulverizer to realize feed volume control, adjust the speed of the nitrogen circulation mechanical pulverizer to realize grinding speed adjustment and adjust the frequency of the classifier to realize fine powder Through the organic coordination of the three process parameters, the input and output volume can be adjusted to achieve precise control of the high and low bulk density index parameters in the range of 0.8 to 1.6g/cm ³ ; (c) Discharge: The powder after each crushing is classified by the classifier installed at the discharge port of the crusher, the powder with coarser particle size remains in the crushing chamber for crushing, and the powder with finer particle size is classified The fan is sent to the cyclone separator for sedimentation, and then discharged through the outlet of the cyclone dust collector into the ton bag and screened by the ultrasonic vibrating screen; (d) Process monitoring: After each crushing and screening, the bulk density of the under-screen material is detected, compared with the process requirements, and the frequency conversion parameters are adjusted in time when deviations occur. 2. A method for controlling the bulk density of iron powder with low bulk density according to claim 1, characterized in that: the crushing motor is Y2-200L2-2 37KW, and the anti-blocking pipe feeder is ZGFE-2L type. 3. A method for controlling the bulk density of iron powder with low bulk density according to claim 1, characterized in that: the adjustment range of the anti-blocking pipe feeder is 0-30HZ. 4. A method for controlling the bulk density of iron powder with low bulk density according to claim 1, characterized in that: the model of the bag filter is HL--100 pulse bag filter, and the air volume of the bag filter is ^2040m3 /h. 5. A method for controlling the bulk density of iron powder with low bulk density according to claim 1, characterized in that: the bulk deviation density of the powder at the outlet of the trap should be <0.05.