KR950000771B1 - Muti-pass roll crusher - Google Patents

Abstract

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Description

Multi-pass roll mill and grinding method

1 is a side view of two parallel rolls used in the present invention.

2 is a longitudinal sectional view of the roll mill shown in FIG. 1 along axis A-A.

* Explanation of symbols for main parts of the drawings

1, 2: primary feed inlet zone 3: secondary feed inlet zone

6, 7: primary grinding zone 10, 11: roll

16: secondary grinding zone 14, 15: end plate

[Field of Invention]

The present invention relates to a multipass roll mill and a method for finely grinding a solid material by a roll mill.

[Background of invention]

Grinding is the conversion of hard material particles into a number of small particles and may include any of grinding, grinding or milling processes.

A device that can be used in the cement or other mineral processing industry to perform grinding of brittle materials of roll mills. Roll mills consist of one or more rolls that pulverize particles of brittle material between one roll and a fixed breaker plate or between rotating rolls.

In the pressure pulverization of the brittle abrasive material in the roll gap of the roll mill, the abrasive material is pulverized by compressive stress. The feed to the roll mill is distributed evenly over the full width of the roll. Alternatively, the feed is known as " choke feed ", i.e., as the feed is fed to the rolls in sufficient quantity to pass the rolls between the rolls to form agglomerate or dense mass material, causing the particles of the feed to break up with each other in the roll gap. It may be dispensed to make a bulk product bed. The product ground in the roll mill is usually conveyed to the classifier as needed after the lump splitting step, and usually over a certain size product is recycled back to the roll mill and mixed with the fresh feed being fed to the roll mill. There are physical limitations on the amount of product recycled through the roll mill with fresh feed.

When attempting to perform highly crushed or ultrafine abrasive stocks, multi-step polishing methods such as pre-grinding, main grinding and fine grinding have been used. For example, a grinding device in which a roll mill, a roll grinder and a ball mill are connected in series may be used, but the overall energy consumption is high as well as the overall cost required. Ball mills are characterized by a high degree of grinding and grind the cement clinker mass with cement powder, but the specific energy required for the ball mill is high.

Mennert's U.S. Patent No. 4,357,287 describes a method for carrying out fine and ultra fine grinding of brittle materials, which is subjected to a stress once between two non-yielding hardened surfaces, such as a roll in a roll mill, at least 500 kg / Under a compressive force of cm 2, energy is sufficiently increased to cause pulverization and significant pulverization and powdering are separated by mechanical stress in a separate device. The advantage of this reference patent is that it is suggested that this stress state is carried out in one pass, significantly reducing the energy required for particle milling. This reference patent does not suggest or suggest a multistressing method which is characterized by saving energy by passing the material through the roll mill more than once.

Here, if the material to be stressed is separately passed through the same roll mill at least twice, the pressure to apply the two stresses is sufficiently high that at least a part of the mill will be pulverized in two passes, resulting in significant energy beyond the process described in US Pat. No. 4,357,287. I realized savings. This energy saving could not be expected at all in the technology of this patent. This multistressing continuous process can be carried out with a novel roll mill having separate primary and secondary inlets and grinding and exit zones so that the materials present in the primary or grinding zones are ground again to the secondary inlet or grinding zone. Minimize mixing with materials in the

Overview of the Invention

The present invention provides a grinding method and apparatus for grinding brittle materials to high purity and having a relatively low total energy consumption.

The present invention relates to a roll mill having two or more different feed inlet zones, at least one primary feed inlet zone to the roll mill by passing through a primary milling zone immediately below the primary feed inlet zone, and a second mill Have at least one secondary feed inlet zone entering the zone. In addition, an appropriate method such as the use of a diaphragm is used so that the product exiting the roll from the primary grinding zone is not intermixed with the product exiting the roll from the secondary grinding zone so that the entire final product is maintained in at least two passageways through the roll. To ensure that The roll mill is designed to pressurize sufficiently high pressure to the primary and secondary feed grinding zones to have an overphase form. In the process of the invention, the fresh feed is first introduced into the roll mill through the primary feed inlet zone into a primary feed milling zone where pressure is sufficiently high that it is pressurized to have a bulk form of at least a portion of the primary feed milling zone. Passed. All materials are collected from the primary feed grinding zone and recycled by entering back through a roll mill via a secondary inlet zone entering the secondary grinding zone. After the final passage through the secondary grinding zone, the material is collected and the mass formed as a result of the passage of the primary and secondary zones collapses. Mass collapse or splitting can be carried out by known methods. For example, standard ball mills or impact mills are used for this purpose. This process is continuous, so that new feed is simultaneously introduced into the primary feed inlet zone while the material from the primary feed grinding zone is recycled to the secondary feed inlet zone. However, it is an important feature of the present invention that fresh feed always enters the roll mill via the primary feed inlet zone and only the final product exits the secondary feed mill zone.

The process of the present invention is suitable for the grinding of brittle materials, such as natural rocks or ores, suitable for the production of cement clinker or cement, for example, products made of natural materials and ground to make cement, melted in a furnace. In particular, the process of the present invention is suitable for cement products, cement clinkers, ores and coal, as well as lime, bauxite, dolomite, alkaline earth carbonates and similar ores or mixtures thereof.

Detailed description of the invention

In a preferred method and apparatus of the present invention, a roll mill is characterized by at least three defined feed inlets and grinding zones defined by a position transverse to the length of the roll face, and the middle of the roll face without extending to both edges of the roll face. It has at least one, preferably only one secondary feed inlet zone and two separate primary feed inlet zones extending inward across the length of the roll face and starting at each edge of the roll face. In a preferred embodiment of the invention, the incoming fresh feed is directed to each of the edges of the roll, i.e., two primary feed inlet zones located adjacent to the end, and then the feed is in communication with each primary feed inlet zone. Passed to the primary feed grinding zone. The primary feed grinding zone occupies the same zone as the feed inlet zone in communication when measured across the length of the roll. The newly ground material is collected as it passes through the roll, taking care not to break up the lumps formed during the first pass, and directed down the middle area of the roll mill, which is finely ground than during the first pass by techniques such as recycling. Change. When the roll mill apparatus of the present invention is operated in a typical manufacturing process, two types of polishing processes are performed simultaneously: a relatively rough polishing process in the primary grinding zone and a finer polishing process in the secondary grinding zone.

In an embodiment of the invention, the freshly introduced feed material is pulverized at a pressure sufficient to form at least some lumps. The freshly ground material from each primary feed grinding zone is placed in the middle of the roll mill that is well bonded using standard recycling equipment known to those skilled in the art and ground at a pressure sufficient to form at least some lumps. Is redirected below the secondary feed inlet zone. It is an important treatment feature of the present invention that the material does not undergo a Henry grinding step to pass through the secondary grinding zone of the roll mill.

Another important feature of the present invention is to minimize or completely exclude intermixing of the intermediate product due to the first pass of the roll mill with the product discharged from the secondary milling zone of the roll mill.

After the final product is discharged from the roll mill, the mass formed during the multipass process is subjected to milling and the final particles are sorted as necessary.

[Brief Description of Drawings]

Other features and advantages of the invention are described in detail with reference to the embodiments shown in the drawings.

In FIG. 2 a roll is shown in the longitudinal direction which is a 1 to 2 roll mill with a secondary roll 11 parallel to the roll 10.

2 shows the gap between two rolls, with roll 11 not shown. The roll 10 has end plates 14, 15 and is divided into three different feed inlet zones, shown as the primary feed inlet zones 1, 2 and the secondary feed inlet zone 3. In an embodiment of the invention, approximately the same amount of fresh brittle material is fed downward from the feed hopper (not shown) to the primary feed inlet zones 1, 2. The material then passes between the rolls and enters the primary grinding zones 6, 7 extending across the length of the roll by the same distance as the feed inlet zone in communication with the primary grinding zone. The material is then discharged through the outlet zones 8, 9 defined by the partitions 12, 13. The pulverized material is recycled to the secondary inlet zone 3 without further pulverization of the mass, thereby exiting the mill through the secondary outlet zone 17 through the secondary grinding zone 16.

That is, the determination of the total area in which the grinding process occurs in the primary grinding zone measured across the length of the roll surface is almost the same as the area provided for grinding in the secondary grinding zone, but this is not an important feature of the present invention and the It can be changed according to the needs of individual practitioners. The exact area depends on variables such as the type of material to be treated and the rated capacity of the roll mill. In a given embodiment, the final determination of the area for each of the feed inlet zones and feed grinding zones depends in part on testing for the particular raw material to be ground, which determination falls within the capabilities of practitioners of ordinary skill in the art. . Continuous operation of the roll mill of the present invention is more necessary to obtain maximum power saving than to obtain a predetermined operation. The area of the feed inlet zone is chosen to prevent overfeeding at the primary feed zone or the secondary feed inlet. However, according to the needs of the individual practicing the present invention, i.e. for capacity control purposes, some of the fines that have passed through the primary grinding zone are recycled through the primary feed inlet zone before being introduced into the secondary feed inlet zone, It will be appreciated that some products that have passed through the primary grinding zone may be recycled through the primary or secondary feed inlet zones. In any case, it is essential to the practice of the present invention that in the roll mill of the present invention the final product is fed only from the secondary milling zone and any other new feed is fed to the mill only via the primary feed inlet zone. The suitable length of the roll face used in the primary inlet zone is from 25% to 400% suitable for the length of the roll face, depending on the material to be treated, and used in the primary grinding zone relative to the length of the roll face used in the secondary grinding zone. Suitable proportions of the length of the roll face are equal to the above percentage range. Thus, in a preferred embodiment of the present invention each of the two primary feed inlet zones extends from each end of the roll up to about 40% of the length of the roll face.

As noted, the material to be treated is pressurized and ground in the feed grinding zone to a pressure sufficient that only a portion of the material has a lump form. The material to be repressurized is fed between parallel rolls of the secondary feed zone under pressure sufficient to form agglomerates. Preferably there is only one secondary feed zone extending from the center point of the roll by at least 10% of the total width of the roll in a roll crossing manner. As pointed out, it is suitable that the secondary feed zone is not in contact with either edge of the grinding roll.

Suitably, the roll mill used in the present invention consists of two parallel cylindrical rolls operating in a reverse rotation manner, with the axes of the rolls properly arranged in the horizontal direction with each other.

The roll surface of the roll mill is smooth, but a protrusion such as a weld bead may be applied to the smooth roll surface as needed to improve the inflow conditions into the roll gap. The resulting pressed slab has an inherent break point. The roll includes an end plate.

The partition used to form the particular feed inlet zone used in the practice of the present invention is formed of any suitable material that can withstand the wear associated with the particular operating conditions used in the process described above. Suitably, the partition can meet the specific conditions of the primary and secondary grinding zones by adjusting the practitioner of the present invention to vary the relative areas of the primary and secondary feed inlets.

The following example is a process described in US Pat. No. 4,357,287, having a partition extending to 20 inches (8 inches) in length and added to form primary and secondary feed inlet zones by the multi-pass test of the present invention. An alis-calmer roll mill with a parallel roll having a width of 15.2 cm (6 inches) for a single pass test is used. Roll mills also include a recycling apparatus suitable for multipass testing used in the process of the present invention. In the apparatus used for the test, there are two primary inlet zones starting at each end of the roll and extending about 5.1 cm (2 inches) along the length of the roll. In the middle of the roll is one secondary feed inlet zone having a length of 10.2 cm (4 inches). Thus, with respect to the distance across the length of the roll, the roll area of the two primary feed inlet zones was about the same as that of the secondary feed inlet zone. The three feed milling zones, two primary feed milling zones and the second feed milling zone, measured along the length of the roll, are the same size as their respective feed inlet zones added together. The material that has passed through each primary feed grinding zone is collected and recycled through the secondary inlet zone so that the mass formed in the primary feed grinding zone is not destroyed. The total energy consumed after the second pass was calculated and compared with the total energy consumed by the single pass mill.

Table 1 shows the values from the "single pass" test and the "multiple pass" test performed on the common materials used in the cement manufacturing process, wherein the materials consisted mainly of limestone. In addition, the numerical value shown in Table 2 is a numerical value with respect to the single pass and multiple pass tests performed on the cement clinker. "Single pass" means that the material has passed through a conventional roll mill without any particular inlet zone. The material is collected and all the mass formed in the passage is destroyed. The purpose of this test is to compare the process of US Pat. No. 4,357,287 to pressurize the material to be crushed only once and the multipass method of the present invention to determine whether energy is saved. As mentioned in the single pass test, the material was fed through a roll mill that was not modified to have specially divided primary and secondary feed inlets and grinder zones in accordance with the present invention. The material was pressurized at a pressure of about 900-2000 psi sufficient in each case to form agglomerates. The material was collected and the formed mass was ground to test the final product to obtain the values shown in Tables 1 and 2.

Table 1 Raw Materials

Table 2 Clinker

In the table, P80 refers to the screen size through which 80% of the material passes. "Supply power" and "final production power" are calculated as the amount of power required for the ball mill to shrink the raw material and final product to a size such that 80% of the raw material and final product can pass through a 200 mesh screen. "Roll mill power" refers to the actual amount of power used in a roll mill to perform a designated milling operation, whether in the prior art method of passing only once each time or the method of the present invention passing each time redundantly. "Supply power" and "roll mill power" have the same meaning for clinker except for the value resulting in 80% of the material obtaining a final product having a size of 3500 blaine.

The test results shown in Tables 1 and 2 indicate that on average about 5-8% additional power savings were realized by pressurizing the material twice compared to the prior art single press method.

It should be understood that many modifications may be made to the above-described embodiments without departing from the scope of the invention.

Claims (16)

One or more primary feed inlet zones (1) for the new feed material may be introduced into a new feed material that is introduced only into the roll mill inside one or more primary feed inlet zones (1,2) and pressurized to a pressure sufficient to form some mass. 2) and two feed inlet zones, one or more secondary feed inlet zones 3 for feed material pressurized more than once by a roll mill, each with a primary feed inlet zone (1, 2) The secondary feed inlet zone 3 is introduced into the interior of the roll mill, which is directed to the corresponding primary feed grinding zones 6 and 7 and the secondary grinding zone 16, respectively, Under the condition that it is finally discharged through the roll mill of the primary grinding zone 16, the feed material formed in the inlet step is further pressurized without breakage of the mass so as to be further pressurized to a pressure sufficient to form several masses. Recycling the passage through the roll mill in the tea feed inlet zone (3). 2. The method of claim 1, wherein the mass formed as a result of the inflow and recycle steps is pulverized after finally passing through the roll mill. 3. The method of claim 2, wherein the material is fractionated after the grinding step. The method of claim 2, wherein the grinding is performed by a ball mill. 3. The method of claim 2, wherein the grinding step is performed with an impact mill. 2. The feed material according to claim 1, characterized in that the feed material in the inlet stage is recycled to the roll mill through one or more primary feed inlet zones (1, 2) before being recycled to one or more secondary feed inlet zones (3). Brittle material grinding method by a roll mill. 2. The feed material according to claim 1, wherein the feed material in the recycle step is recycled to the roll mill through one of at least one primary feed inlet zone (1, 2) or at least one secondary feed inlet zone (3). Brittle material grinding | pulverization method by the roll grinding | pulverizer made into a mold. 2. The roll mill as claimed in claim 1, wherein the brittle material is used for cement products and is selected from the group consisting of cement clinker, ore, coal, lime, bauxite, dolomite and alkaline earth carbonates and mixtures thereof. Brittle material grinding method by. 2. Method according to claim 1, characterized in that the roll mill comprises a pair of rolls (10,11) whose axes are parallel and horizontal to each other. 10. Method according to claim 9, characterized in that the roll mill has two separate primary feed inlet zones (1,2) and one secondary feed inlet zone (3). 12. The method according to claim 10, wherein each primary feed inlet zone (1,2) is located separately at each edge of the rolls (10,11) and each primary feed inlet zone (2,3) is a roll (10,11). A method of crushing brittle material by a roll mill, characterized in that it extends separately from each edge along the length of the roll up to 40% of the total length. 2. The method of claim 1, wherein the method is a continuous process. At least one primary for the new feed material, which can be pressurized to a pressure sufficient to form several masses and directed to the corresponding primary feed milling zones 6,7 and secondary feed milling zones 16, respectively Two feed inlet zones (1,2) and one or more secondary feed inlet zones (3) for feed material pressurized more than once by a roll mill, and at a pressure sufficient to form some mass Roll recycling means for recycling the pressurized material in the primary feed grinding zone to pass into the roll mill of the secondary feed inlet zone (3) without breaking the mass so as to be more pressurized. 14. The roll mill as claimed in claim 13, wherein the roll mill comprises a pair of rolls (10,11) whose axes are parallel and horizontal to each other. 15. The roll mill as claimed in claim 14, wherein the roll mill has two separate primary feed zones (1,2) and one secondary feed inlet zone (1,2). 15. The method according to claim 14, wherein each primary feed zone (1,2) is located separately at each edge of the roll and extends separately from each edge across the side of the roll to 40% of the total width of the roll (10,11). Roll mill, characterized in that.