CN110681479A

CN110681479A - Secondary screening and dewatering device and method for concrete system

Info

Publication number: CN110681479A
Application number: CN201910975540.4A
Authority: CN
Inventors: 卞小草; 帅小根; 丁高俊; 雷畅; 肖彦; 龙昌满; 刘培; 魏鹏帅; 耿祺; 王立军
Original assignee: Changjiang Institute of Survey Planning Design and Research Co Ltd
Current assignee: Changjiang Institute of Survey Planning Design and Research Co Ltd
Priority date: 2019-10-14
Filing date: 2019-10-14
Publication date: 2020-01-14

Abstract

The invention relates to a secondary screening and dewatering device and a secondary screening and dewatering method for a concrete system, wherein the device comprises a charging bucket and a secondary screening machine which are sequentially connected, the secondary screening machine comprises a fixed grid screen for screening waste materials larger than 150mm, a mechanical vibration screen group for screening aggregate with the aggregate size of 20 mm-150 mm and a dewatering screen for screening aggregate with the aggregate size smaller than 20mm, and the mechanical vibration screen group and the dewatering screen are respectively communicated with a mixing plant through a belt conveyor. The device can utilize the fine aggregate of small particle size comprehensively, has effectively avoided the fine aggregate to wash and has leaded to the moisture content too high.

Description

Secondary screening and dewatering device and method for concrete system

Technical Field

The invention belongs to the technical field of civil engineering concrete, and particularly relates to a secondary screening and dewatering device and method for a concrete system.

Background

The large-scale hydropower engineering built and built at home and abroad has great demand on cast-in-place concrete, and the productivity of the concrete becomes a main factor of the construction progress, quality and investment of the engineering. In most of the current engineering applications, a secondary screening system for sand aggregate is arranged in the concrete production link, and according to the industry specifications established by relevant national departments, fine aggregate (about 6-8% of the total amount of sand aggregate) with the size smaller than 5mm under a secondary screening screen is not allowed to be directly mixed with concrete and is usually used as waste material, which has become an industry consensus.

The flow diagram of the existing secondary screening device of a concrete system is generally shown in fig. 1, broken stone aggregates are stored in a charging bucket 100 and screened by a secondary screening machine 200 at any time, the screened aggregates with the size of 5 mm-150 mm can directly enter a mixing plant 400 for concrete production, then are transported to a construction part by a concrete transport vehicle 500, and the screened fine aggregates with the size smaller than 5mm are directly discarded and enter a material dump 300. Discarding fine aggregates smaller than 5mm in the secondary screening not only causes resource waste, but also shows that the quality control of finished aggregates is too conservative. In addition, the sandstone materials are broken due to falling, collision and other reasons in the stacking and transportation processes, the generated fine aggregates with the particle size smaller than 5mm and stone powder with extremely small particle size easily cause the phenomenon of powder coating on the surfaces of the fine aggregates, the water content is too high (more than 15 percent) in the washing process, and the use of the fine aggregates is restricted.

Disclosure of Invention

The invention aims to overcome the problems in the prior art and provides a secondary screening and dewatering device for a concrete system, which can utilize fine aggregates with small particle sizes and avoid overhigh water content of the fine aggregates.

The secondary screening and dehydrating device of the concrete system comprises a charging bucket and a secondary screening machine which are sequentially connected, wherein the secondary screening machine comprises a fixed grid sieve for screening waste materials larger than 150mm, a mechanical vibrating screen group for screening aggregate of 20 mm-150 mm and a dehydrating screen for screening aggregate of 20mm, and the mechanical vibrating screen group and the dehydrating screen are respectively communicated with a mixing plant through a belt conveyor.

Further, the mechanical vibrating screen group sequentially comprises a first vibrating screen for obtaining aggregate of 80-150 mm, a second vibrating screen for obtaining aggregate of 40-80 mm and a third vibrating screen for obtaining aggregate of 20-40 mm according to the screening sequence; and the aggregates obtained by the first vibrating screen, the second vibrating screen and the third vibrating screen are respectively conveyed to a mixing plant through a belt conveyor.

The secondary screening and dewatering device for the concrete system comprises the following steps,

(1) storing the crushed stone aggregate in a charging bucket;

(2) placing the crushed stone aggregates in the material tank into a secondary screening machine for screening, and conveying the 20-150 mm aggregates obtained by the mechanical vibrating screen group into a mixing plant through a belt conveyor for producing concrete;

(3) the residual aggregate of 20mm is washed, and the aggregate of 20mm after being dehydrated by a dehydration screen is directly transported to a mixing plant by a belt conveyor.

Further, the 20 mm-150 mm aggregate is sequentially screened into 80 mm-150 mm aggregate, 40 mm-80 mm aggregate and 20 mm-40 mm aggregate in the mechanical vibrating screen group, and is respectively transported to a mixing plant through a belt conveyor.

Further, in the step (3), the moisture content of the aggregate with the thickness of less than 20mm after being dehydrated by a dehydration screen is less than 6.5 percent.

The invention has the beneficial effects that:

the secondary screening and dewatering device for the concrete system provided by the invention cancels a 5 mm-aperture vibrating screen in a secondary screening machine of the original concrete system, and replaces the 5 mm-aperture vibrating screen with the dewatering screen, so that the problem of overhigh water content of aggregate with the particle size of less than 20mm caused by washing can be solved, and the aggregate with the particle size of less than 20mm can directly enter a mixing plant to produce concrete after being treated.

The secondary screening method for the concrete system can completely use fine aggregate which is less than 5mm and is generated by the original concrete system for producing the concrete, ensures that the mixing proportion of the concrete meets the standard requirement by controlling the using amount of the fine aggregate, namely the sand, in the concrete, can save the amount of the engineering aggregate by about 6-8 percent, and has obvious economic benefit.

Drawings

FIG. 1 is a schematic flow diagram of a secondary screening device of a concrete system in the prior art;

FIG. 2 is a schematic structural diagram of a secondary screening and dewatering device of the concrete system of the present invention;

FIG. 3 is a schematic flow diagram of a secondary screening and dewatering device of the concrete system of the present invention;

in the figure: a charging bucket 100; a secondary screening machine 200; a fixed grid 210; a mechanical shaker bank 220; an 80mm vibrating screen 221; a 40mm vibrating screen 222; a 20mm vibrating screen 223; a dewatering screen 230; existing secondary screening machines 200'; a stock dump 300; a mixing plant 400; a transport vehicle 500.

Detailed Description

The embodiments of the present invention will be described in detail below with reference to the drawings, but the embodiments are not intended to limit the present invention and are merely examples.

The secondary screening and dewatering device of the concrete system shown in fig. 2-3 comprises a charging bucket 100 and a secondary screening machine 200 which are connected in sequence; the secondary screening machine 200 sequentially comprises a fixed grid sieve 210, a mechanical vibration sieve group 220 and a dewatering sieve 230 from top to bottom. The fixed screen 210 screens aggregates having a particle size of more than 150mm into a reject.

The mechanical vibrating screen group 220 is composed of a first vibrating screen 221 with an aperture of 80mm, a second vibrating screen 222 with an aperture of 40mm, and a third vibrating screen 223 with an aperture of 20 mm. Aggregate with the particle size of 80-150 mm can be obtained on the first vibrating screen 221, the aggregate is directly conveyed to the mixing plant 400 through a belt conveyor, the aggregate with the particle size of less than 80mm passes through the first vibrating screen 221 and then falls into the second vibrating screen 222 for screening, the aggregate with the particle size of 40-80 mm obtained on the second vibrating screen 222 is conveyed to the mixing plant 400 through the belt conveyor, the aggregate with the particle size of less than 40mm continuously downwards passes through the third vibrating screen 223, the obtained aggregate with the particle size of 20-40 mm is conveyed to the mixing plant 400 through the belt conveyor, the rest aggregate with the particle size of less than 20mm can be directly conveyed to the mixing plant 400 through the belt conveyor after being dehydrated through the dehydrating screen 230 and is mixed with the coarse aggregate separated before, and the mixing ratio of concrete is ensured to meet the standard requirement.

The use of the device comprises the following steps:

firstly, storing crushed stone aggregates in a charging bucket 100;

secondly, screening the crushed stone aggregate by using an improved secondary screening machine 200, respectively screening waste materials with the thickness of more than 150mm, aggregate with the thickness of 80 mm-150 mm, aggregate with the thickness of 40 mm-80 mm and aggregate with the thickness of 20 mm-40 mm, and conveying each batch of aggregate into a mixing plant 400 through a belt conveyor;

thirdly, washing the aggregate which is sieved and removed and has the diameter of 20mm, and then dehydrating the aggregate by a dehydration screen 230, wherein the aggregate which has the diameter of 20mm is conveyed to a mixing plant 400 by a belt conveyor;

and fourthly, the prepared concrete is transported to a construction site by a transport vehicle 500.

The detection shows that the moisture content of the aggregate with the diameter of less than 20mm is 6.23 percent.

In order to more clearly illustrate the advantages of the improved concrete system secondary screening dehydration method and device compared with the original concrete system secondary screening dehydration method and device, the benefit generated by the application of the method and device in a large hydraulic engineering is estimated, 314.3 ten thousand meters 3 concrete is commonly used in the hydraulic engineering, the fine aggregate smaller than 5mm is about 14.8 ten thousand tons, and the economic benefit is as follows:

(1) the cost of the waste slag is 232.66 ten thousand yuan, the labor cost, the material cost and the mechanical cost which can be consumed for cleaning the waste materials with the diameter less than 5mm are required, the unit price of the waste slag is 15.72 yuan/t, 14.8 ten thousand tons of reusable sand are required, and the cost of the waste slag can be saved.

(2) The material cost of finished sand equivalent to the waste material is saved, the finished sand is saved by about 14.8 ten thousand tons, and the cost of the finished sand is saved by about 501.42 ten thousand yuan according to the contract unit price of 33.88 yuan/ton;

the total cost is saved by about 734.08 ten thousand yuan.

Generating a benefit statistics table

Saving items	Waste slag management cost	Cost of finished sand	Total up to
				Amount (Wanyuan)	232.66	501.42	734.08

Claims

1. Concrete system secondary screening dewatering device, its characterized in that: including material jar (100) and secondary screening machine (200) of connecting in order, the secondary screening machine is including being used for sieving and removing fixed grid sieve (210) of >150mm abandonment material, mechanical vibration sieve group (220) that are used for sieving 20mm ~ 150mm aggregate and dewatering screen cloth (230) that are used for sieving <20mm aggregate, mechanical vibration sieve group (220) with dewatering screen cloth (230) communicate respectively through the belt feeder and mix building (400).

2. The secondary screening and dewatering device of a concrete system as claimed in claim 1, wherein: the mechanical vibrating screen group (220) is sequentially provided with a first vibrating screen (221) for obtaining aggregate of 80-150 mm, a second vibrating screen (222) for obtaining aggregate of 40-80 mm and a third vibrating screen (223) for obtaining aggregate of 20-40 mm according to the screening sequence; the aggregates obtained by the first vibrating screen (221), the second vibrating screen (222), and the third vibrating screen (223) are respectively transported to a mixing plant by a belt conveyor.

3. The secondary screening dehydration method of the concrete system is characterized in that: the secondary screening dewatering apparatus using the concrete system of claim 1, comprising the steps of:

(1) storing crushed stone aggregate in a charging bucket (100);

(2) crushed stone aggregates in the material tank (100) are placed into a secondary screening machine (200) for screening, and 20-150 mm aggregates obtained by a mechanical vibrating screen group (220) are transported into a mixing plant (400) through a belt conveyor for concrete production;

(3) the residual aggregate of 20mm is washed, and the aggregate of 20mm dehydrated by the dehydration screen (230) is directly transported to a mixing plant (400) through a belt conveyor.

4. The secondary screening dehydration method of concrete system according to claim 3 characterized in that: the aggregates with the diameter of 20 mm-150 mm are sequentially screened into aggregates with the diameter of 80 mm-150 mm, aggregates with the diameter of 40 mm-80 mm and aggregates with the diameter of 20 mm-40 mm in the mechanical vibration screen group (220), and the aggregates are respectively transported to a mixing plant (400) through a belt conveyor.

5. The secondary screening dehydration method of concrete system according to claim 3 characterized in that: in the step (3), the moisture content of the aggregate with the diameter of less than 20mm after being dehydrated by the dehydration screen (230) is less than 6.5 percent.