JPH0795024B2 - Grinding test method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a granular material such as coal pulverized by a pulverizer,
The present invention relates to a test method and a test device for evaluating pulverizability and frictional properties.

The term "grindability" as used herein refers to a particle size when crushed under a certain condition, and from a different point of view, it can be said to be the time (power) required for crushing to the same particle size. Also, "friction characteristics" means the coefficient of wall friction between the surface of rolling elements and rolls and the granular material,
It is a comprehensive characteristic relating to friction, including the internal friction coefficient between particles of a granular material.

[Conventional technology]

As a conventional crushing test technique, there is a hard glove crushability test method defined in JIS M8801-4. This was to evaluate the grindability by the change in the particle size of the sample after grinding for a certain period of time. More specifically, the surface water content is 0.
%, And the particle size adjusted to 14 ^# ~ 28 ^# (1.09 ~ 0.54 mm) was crushed for 4 minutes at 15 revolutions per minute for 4 minutes using a device with almost the same configuration as in Fig. 1 but no gap sensor (10). Of sample
The 200 ^# (75 μm) pass amount is measured and converted to grindability.

[Problems to be solved by the invention]

When a certain type of coal (coal with poor friction characteristics) is crushed in a vertical roller mill, the biting into the roll is poor, and the load of the roll is not sufficiently applied to the coal layer, so the coal cannot be crushed efficiently, In some cases, the mill capacity estimated from the pulverizability obtained by the hard glove method was much lower. Further, since the amount of lift of the roll is small, the vibration of the mill is large and the mechanical life of each part of the mill may be reduced.

Here, the "lift amount" is the thickness of the powder or granular material that is caught between the bottom surface of the container and the roll or rolling element, and the load platform and the like in the crushability test device including the rolling element. It is called like this because it lifts. The lift amount of zero is a state in which the rolling element and the container are in contact with each other. For example,
If you try to bite a small steel ball instead of a powder or granular material, the steel ball will be pushed away while the rolling element is transferred, and the rolling element and the container will come into contact. In other words, the steel ball has low friction (poor friction characteristics) and bites poorly.

Such a rolling element or roll lift is shown in FIG. If the frictional characteristics are good, the biting angle θ becomes large as shown in FIG. 4 (a), and as a result, the number of powder particles t ₁ to be bitten and ground becomes large, and the lift amount 1 also becomes large. On the contrary, if the friction characteristics are poor, it is shown in Fig. 4 (b).
As described above, the biting angle θ becomes smaller, the amount of powdery particles t _{1 to} be bitten in becomes smaller, and the lift amount 1 becomes smaller.

In a roller mill, if the biting angle θ is small and the crushing amount is small, but if the coal supply amount is further increased, the thickness of the coal layer continues to increase, and finally the roll only pushes the coal layer apart, causing a large vibration. Occurs. Further, generally, the lift amount of the rolling element is affected by the amount of the powder or granular material sample, so that the amount of the sample to be used is constant in the pulverization test.

As described above, the manner in which the granular material such as coal is crushed is greatly influenced by the frictional characteristics, and therefore its prediction and evaluation of the mill capacity cannot be performed only by the pulverizability, and it is necessary to include the frictional characteristics. However, there has been no conventional evaluation of frictional characteristics, and there has been no apparatus for evaluation.

[Means for solving problems]

In order to solve the above problems, the present invention puts a sample and a rolling element in a container, crushes the sample by rolling while pressing the rolling element with a constant load, and lift amount of the rolling element. Crushing test method, which is characterized by rolling until the lift amount becomes almost constant, and a container for storing the sample, a rolling element arranged in the container, and a constant load on the rolling element. The present invention proposes a crushing test apparatus characterized by having a means for rolling while pressing with and a means for measuring the lift amount of the rolling element.

[Operation] In the present invention, the lift amount of the rolling element during the crushing test is measured, and its steady value is used for the evaluation of the friction characteristics.

〔Example〕

An embodiment of the present invention will be described with reference to FIG. (1) in the figure
Is a container, that is, a crushing chamber, which is shaped so that the rolling elements can roll. In the crushing chamber (1), a plurality of balls (2) as rolling elements are positioned and arranged by a pressing plate (3). The pressing plate (3) is fixed to a vertical rotating shaft (5) supported by a bearing (4).
(6) is a gear fixed to the upper part of the rotary shaft (5), and a second gear (7) meshing with the gear (6) is connected to a drive device such as an electric motor (not shown). In addition, the rotary shaft (5)
A load table (8) is provided at the upper end of the and a weight (9) of a predetermined weight is placed. A gear cap sensor (10) is provided below the end of the gear (6).

In such an apparatus, the sample S is put in the crushing chamber (1), the weight of the ball (2) is applied to the ball (2), that is, a constant downward load is applied, and the driving device (not shown) is connected to the gear (7). Drive the holding plate (3) to the rotating shaft (5)
The ball (2) is rotated by rotating the ball (2) around, and the sample S is bitten into the ball (2) and crushed. On the other hand, the amount of lift of the ball (2), which is a rolling element, due to the biting of the sample is measured by measuring the gear up with the lower surface of the gear (6) with the gear up sensor (10). At this time, the lift amount of the rolling element changes with time as shown in FIG. 2, and its pattern varies depending on the coal, but since it drops to a substantially constant value with the passage of time, its steady value gives the friction characteristic. Used to evaluate.

There is a positive correlation between the lift amount of the rolling elements of the crushing test device and the roll lift amount of the vertical roller mill, as shown in FIG. Therefore, the frictional characteristics obtained by this crushing test are used for selecting crushing means (selecting whether the vertical roller mill is a tube mill, etc.) or setting the capacity of the mill. That is, if friction characteristics are poor, use a tube mill,
Even if it is within the range of friction characteristics that can be crushed by a roller mill, it is used to estimate a small treatment amount and select a large roller mill.

Although balls are used as the rolling elements in the above-mentioned embodiment, a tire type roller such as a roller mill or a truncated cone type roll can also be used. Further, the rolling element may be rotated by rotating the container instead of rotating the rolling element by the pressing plate as in the above embodiment.

〔The invention's effect〕

According to the present invention, it is possible to estimate the roll lift amount of a vertical roller mill with a small amount of sample, and it is possible to evaluate the frictional characteristics when pulverizing granular material such as coal.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention, FIG. 2 is a diagram showing changes in lift amount of rolling elements over time, and FIG. 3 is a relationship between lift amount of rolling elements and lift amount of rolls. And FIG. 4 are diagrams for explaining the biting angle and the lift amount of the rolling element or the roll. (1) ... Grinding chamber (container); (2) ... Ball (rolling element); (3) ... Presser plate; (4) ... Bearing; (5) ... Rotating shaft; (6), ( 7) …… Gear; (8) …… Loading platform; (9) …… Weight; (10) …… Gear sensor; S …… Sample.

(72) Inventor Takeshi Kunimoto 2-5-1, Marunouchi, Chiyoda-ku, Tokyo Sanryo Heavy Industries Co., Ltd. (72) Yoshitaka Koga 2-5-1, Marunouchi, Chiyoda-ku, Tokyo Sanryo Heavy Industries Incorporated (56) References JP-A-59-50341 (JP, A)

Claims (2)

[Claims] 1. A sample and a rolling element are put in a container, and the rolling element is crushed by rolling while pressing the rolling element with a constant load, and the lift amount of the rolling element is measured to obtain the same lift amount. The crushing test method is characterized by rolling until the temperature becomes almost constant. 2. A container for storing a sample, a rolling element arranged in the container, a means for rolling the rolling element while pressing the rolling element with a constant load, and a means for measuring the lift amount of the rolling element. A crushing test device comprising: