JPH10337492A - Production of sand - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce the sand of JIS size with a crusher by returning the whole of the oversize among the crushed material passed through a crusher and a part of the product size to the crusher and recrushing them. SOLUTION: The raw material passed through a centrifugal crusher 1 and crushed is separated by a first screen 2 into the product size and oversize. The first screen 2 and the crusher 1 are communicated through a circulating pipe, a conveyor, etc. The product size from the first screen 2 is separated by a second screen 3 to obtain the undersize which is dropped as a product, and the oversize is separated in a specified ratio. The second screen 3 and the crusher 1 are also communicated by a circulating pipe, a conveyor, etc., a part of the separated specified size is returned to the crusher 1, and the separated other part is dropped as a product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sand making method.

[0002]

2. Description of the Related Art As a method for producing sand, there is a method using a crusher such as a centrifugal crusher. In this method, as shown in FIG. 5, a raw material is crushed by a centrifugal crusher 1 or the like, and then sieved by a screen 2. Products having a particle size of a product size are sieved, and products having a product size over are returned to the centrifugal crusher 1 or the like for crushing.

[0003]

There is a JIS standard for the particle size of sand as a product, and it is necessary that the particle size falls between two broken lines shown in the graph of the particle size accumulation curve in FIG. The raw material before crushing usually has a particle size distribution along a curve connecting the x points. In the distribution of the products obtained by the above-mentioned conventional crushing method, the particle diameters are distributed by a curve connecting the ● points. That is, the product obtained by the conventional method deviates from the JIS standard. This result does not change much even if the crushing capacity of the centrifugal crusher 1 or the like is increased, and it can be said that this is the limit of the existing capacity of the centrifugal crusher 1 or the like.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, and an object of the present invention is to provide a method for producing JIS standard size sand using a crusher. .

[0005]

Means for Solving the Problems As a means for solving the above-mentioned problems, in a method for producing sand using a crusher, a crushed material having passed through the crusher has a particle size of a product size over. The present invention provides a sand-making method characterized by returning all of the product to the crusher, and returning part of the product size to the crusher and crushing again. Hereinafter, referring to the drawings,
An embodiment of the present invention will be described.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION

<A> Structure of Apparatus As shown in FIG. 1, the apparatus for performing the sand making method of the present invention comprises a crusher such as a centrifugal crusher 1, a first screen 2 and a second screen 3. It is composed of

[0007] The centrifugal crusher 1 puts the crushed raw material into a high-speed rotating rotor, discharges the crushed raw material to the periphery from a discharge opening formed in the rotor peripheral surface by centrifugal force, and places the crushed raw material around the rotor. This is a device for crushing the raw material by colliding with a dead bed, anvil or the like provided.

The first screen 2 is an apparatus for sieving the crushed raw material that has passed through the centrifugal crusher 1 into a product size particle size and a product size over particle size.
The first screen 2 and the centrifugal crusher 1 are connected by a circulation pipe or a conveyor.

The second screen 3 further sieves the particle size of the product size sieved in the first screen 2 to a predetermined particle size, and drops the product having a particle size equal to or smaller than the predetermined particle size to a predetermined particle size. The above is an apparatus for dividing at a predetermined ratio.

The second screen 3 and the centrifugal crusher 1 also communicate with each other by a circulation pipe or a conveyor, and a part of the divided predetermined particle size is reduced to the centrifugal crusher 1 and divided. Other parts are dropped as products.

The crusher used in the present invention includes, in addition to a centrifugal crusher, an impact crusher, a rod mill,
Other known crushers such as a vibration mill, a cage mill, a ball mill, a vertical roller mill, and a cone crusher can also be used.

<B> Crushing method The raw material crushed and passed by the centrifugal crusher 1 is sieved by the first screen 2 and the product size is changed to the second screen 3
Then, as indicated by the arrow 4, the product size over is returned to the centrifugal crusher 1 and crushed.

In the second screen 3, the product size product is further sieved with a predetermined particle size, and the under size product is dropped as a product (arrow 5). Among them, those smaller than the product size are separated from the product sand by an air classifier or the like.

[0014] The over screened by the second screen 3
At the predetermined ratio of a: (1-a), the size is sorted into a product that is dropped as a product (arrow 6) and a product that is returned to the centrifugal crusher 1 (arrow 7). By crushing by circulating the product size by the above closed circuit, J
Products within the IS standard can be obtained.

[0015]

FIG. 2 shows the mesh of the first screen 2 as 2.75.
mm, the mesh of the second screen 3 is 1.2 mm, and the size from 1.2 mm to 2.75 mm sieved with the second screen 3 is centrifuged at a ratio of 30%, 50%, 70%. This is an embodiment in the case of returning to the crusher 1. It can be seen that the cumulative particle diameter curves for each return ratio fall within the range of the JIS standard indicated by the broken line.

FIG. 3 shows the mesh of the first screen 2 as 3
FIG. 4 shows an embodiment in which the mesh of the first screen 2 is changed to 3.5 mm and the other conditions are the same, and all of them are within the range of the JIS standard indicated by the broken line. .

In addition, the present invention is not limited to the above-described embodiment, and by examining the distribution of the particle size of the product size, by appropriately changing the conditions such as the screen mesh and the return ratio so as to be within the JIS standard, JIS standard products can be obtained by dealing with differences in size and quality of crushed raw materials or differences in the capabilities of centrifugal crushers.

[0018]

According to the present invention, by returning a part of the product having a particle size to the crusher, the product size of the sand within the JIS standard, which was conventionally impossible as the capability of the crusher itself, is contained. Succeeded.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a particle size accumulation curve.

FIG. 3 is an explanatory diagram of a particle size accumulation curve.

FIG. 4 is an explanatory diagram of a particle size accumulation curve.

FIG. 5 is an explanatory view of a conventional technique.

Claims (1)

[Claims] 1. A method for producing sand using a crusher, wherein the crushed material having passed through the crusher has a particle size of product size o.
A sand making method characterized in that all the bars are returned to the crusher, and a part of the product size is returned to the crusher and crushed again.