JPH07103875A - Method for detecting fineness of powder - Google Patents

Abstract

PURPOSE:To enhance accuracy in measurement by causing circular motion of a sieve frame along a stopper provided for a spray nozzle thereby sustaining constant the distance between the tip of nozzle and the mesh plane of sieve along with the inclination thereof. CONSTITUTION:The mass of a cleaned and dried 45mum sieve 8 is measured and fixed to a sieve frame 6. A sample 7 of 1g is then placed on the sieve mesh 8 and entirely wetted by feeding water flow silently. Pressure of a spray nozzle 1 is regulated at 0.7+ or -0.05kgf/cm<2> through a regulation valve 4 and the sample 7 is subjected to spray shower for 1 min while rotating the frame body 6 horizontally at a rate of 1 revolution/sec along a stopper 2. Subsequently, the sieve 8 is removed and supported in a dryer at 100-110 deg.C such that the air can pass freely on the rear surface of the sieve 8 thus drying the sample 7 for about 15 min. The sieve 8 and the sample 7 are then cooled down to the room temperature in a desiccator and the mass thereof is weighed up to 0.1mg and the mass of the sieve 8 at the time of starting test is subtracted therefrom to determine the residue thus evaluating the fineness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fineness test method for sieving a sample on a sieve with a spray shower.

[0002]

2. Description of the Related Art Generally, the fineness of powder cannot be unambiguously determined only by its specific surface area, and therefore the measurement of the residue by a mesh sieve is also used. Conventionally, as for the fineness of cement, the Blaine specific surface area and the residue due to the 90 μm mesh sieve were mainly measured. However, in recent years, it has become less likely that the cement contains coarse particles that can be measured as the residue of a 90 μm mesh sieve. Therefore, instead of the 90 μm mesh sieve, measuring the fineness of powder using a 45 μm mesh sieve is one of the quality control measures for cement. It came to be done as one.

As a fineness test method using a 45 μm mesh sieve, there are ASTM C430-83 and JCAS-KS-02 based on this. The outline of this test method is
First, 1 g of a sample is weighed on a 45 μm mesh sieve set at the bottom of a stainless steel cylinder having an inner diameter of 50 mm and a depth of 100 mm, and sieved by a spray shower for 1 minute. Next, the residue on the sieve was removed from the cylinder together with the sieve, dried at 100 to 110 ° C for about 15 minutes, and then weighed.
The weight of the sieve is subtracted to obtain the residue of the sieve.

[0004]

However, in the conventional test method, when sieving with a spray shower,
It was difficult to keep the distance and inclination between the tip of the nozzle and the screen surface of the sieve constant. That is, place the tip of the spray nozzle at a position within 10 mm from the upper end of the sieving frame, adjust the pressure of the spray nozzle to 0.7 ± 0.05 kgf / cm ² , and rotate the sieve horizontally at a rate of 1 rotation per second. While exercising, spray shower the sample for 1 minute. While monitoring the water pressure gauge and clock, the shape is 100 mm with one hand.
Since a sieving frame of × 60 mmφ and a weight of about 800 g was operated, the distance from the nozzle tip to the sieving mesh surface and the inclination between the nozzle tip and the sieving mesh surface changed. Therefore, the measurement values vary and the measurement accuracy is poor.

An object of the present invention is to overcome the above-mentioned difficulties and to provide a fineness test method which is excellent in measurement accuracy even though the equipment used is simple.

[0006]

Means for Solving the Problems The present inventor has conducted extensive studies and found that the above problems can be solved by providing a stopper on a spray nozzle, and completed the present invention. That is, the gist of the present invention is a fineness test method in which a spray nozzle is provided with a stopper, and a sieve on the sieve is sieved by a spray shower while the sieve frame is circularly moved along the stopper.

The present invention will now be described in detail with reference to the drawings. FIG. 1 is an explanatory view showing an example of a measurement state of the fineness test method of the present invention. In FIG. 1, the spray nozzle 1 is provided with a stopper 2 at a position 10 mm from its tip. Further, a pressure gauge 3 and a regulating valve 4 are provided to regulate the pressure. A mesh sieve 8 is fixed to the sieve frame 6 by screwing metal fittings 9. Sample 7 on mesh sieve 8
On the other hand, the spray shower is performed by the spray water 5 from the spray nozzle 1.

A method for testing the fineness of cement by using, for example, a 45 .mu.m mesh sieve will be described with reference to FIG.
It is as (d). (A) After measuring the mass of the washed and dried 45 μm mesh sieve 8, the mass is fixed to the sieve frame 6, 1 g of the sample 7 is weighed on the mesh sieve 8 and the whole sample is wetted by a gentle stream of water.

(B) The pressure of the spray nozzle 1 is 0.7 ±
The pressure is adjusted to 0.05 kgf / cm ^2, and the spray shower of the sample 7 is performed for 1 minute while moving the sieve frame 6 along the stopper in a horizontal circular motion at a rate of 1 rotation per second.

(C) A state in which the mesh sieve 8 is removed from the sieve frame 6 and the air freely passes through the lower surface of the mesh sieve 8 in a dryer (not shown) having an internal air temperature of 100 to 110 ° C. The sample 7 is dried for about 15 minutes by supporting the mesh sieve 8 on the above.

(D) After the mesh sieve 8 and the sample 7 are cooled to room temperature in a desiccator (not shown), their mass is adjusted to 0.
Weigh up to 1 mg and subtract the mass of the mesh sieve 8 at the start of the test to obtain the sieve residue of Sample 7.

FIG. 2 is an explanatory view showing an example of a mounted state of the stopper used in the present invention, and FIG. 3 is a sectional view taken along the line AA of FIG.

2 and 3, the stopper 2 has a cylindrical portion 2a and a flat plate portion 2b, and is fixed to the spray nozzle 1 with a fixing bolt 2c. The distance between the bottom surface of the flat plate portion 2b and the tip of the spray nozzle 1 is adjusted to 10 mm.
If necessary, the stopper 2 has a reinforcing portion 2e of the flat plate portion 2b.
May be provided. The shape of the flat plate portion 2b may be square, hexagonal, octagonal, or circular other than triangular. The shape of the tubular portion may be polygonal other than circular.

The tubular portion 2a, the flat plate portion 2b, and the reinforcing portion 2e.
The material of is plastic, metal, ceramic, glass or the like. The tubular portion 2a, the flat plate portion 2b, and the reinforcing portion 2e, which are made of transparent plastic, are suitable because the sieving frame is easy to see from the top during operation. The fixing bolt 2c can be made of metal, plastic, or the like, but stainless steel is preferable from the viewpoint of durability. The slip prevention material 2d can be made of rubber, plastic, or the like, and the rubber tube is preferable because of its elasticity.

[0015]

In the present invention, as described above, the spray nozzle having the stopper provided at the position above the tip of the spray nozzle is used. Since the sieving frame is moved circularly along the stopper, the distance between the tip of the spray nozzle and the sieving mesh surface can be kept constant during the operation. Also, the mesh sieve can be rotated horizontally.

[0016]

[Example] Cement Association standard sample for fineness measurement (10
2-F, 45 μm residue 5.4%) was used to perform a performance comparison experiment between the fineness test method of the present invention and the conventional method. An inspector A having a deep measurement experience and an inexperienced B are each of the above standard samples by the method of the present invention (experiment 1) using a stopper shown in FIG. 2 and the conventional method (experiment 2) not using a stopper. The measurement was performed 10 times, and the average value and the standard deviation were obtained. The results are shown in Table 1.

[0017]

[Table 1]

It can be seen from Table 1 that the fineness test method of the present invention has a higher accuracy of measured values and a significantly lower precision (variation) of the measured values as compared with the conventional method.

[0019]

As described above, according to the fineness test method of the present invention, since the sieving frame is circularly moved along the stopper provided in the spray nozzle, the distance between the nozzle tip and the sieving mesh surface can be controlled. It is kept constant inside, and the screen surface of the sieve rotates horizontally. Therefore, the measurement accuracy (accuracy and precision) is significantly improved.

Further, the stopper used in the present invention has a simple structure, is less likely to be damaged, and can be manufactured at a low cost. Therefore, the present invention provides a fineness test method with excellent measurement accuracy while using simple equipment.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a measurement state of a fineness test method of the present invention.

FIG. 2 is an explanatory view showing an example of a mounted state of a stopper used in the present invention.

3 is a cross-sectional view taken along the line AA in FIG.

[Explanation of symbols]

 1 Spray Nozzle 2 Stopper 2a Cylindrical Part 2b Flat Plate Part 2c Fixing Bolt 2d Displacement Stopper 2e Reinforcement Part 3 Pressure Gauge 4 Control Valve 5 Spray Water 6 Sieve Frame 7 Sample 8 Net Sieve 9 Screw-in Metal Fitting

Claims (1)

[Claims] 1. A test method for fineness of powder, characterized in that a spray nozzle is provided with a stopper, and a sieve on the sieve is sieved by a spray shower while the sieve frame is circularly moved along the stopper.