JPS60241944A - Method and apparatus for desalting sea sand - Google Patents

Abstract

PURPOSE:To obtain continuously sand having >=0.04% salt content from sea sand by adding a specified amt. of fresh water to drained sea sand and agitting, and then supplying the raw material to a centrifugal washing-classification dehydrator by pneumatic transportation. CONSTITUTION:Sea sand in a feed hopper is taken out by a vibrating feeder in appropriate portions, and sent to an agitator 2 at the succeeding stage by the first belt conveyor. Then the raw material is transported to a centrifugal washing-classification dehydrator 3 at the succeeding stage by the second belt conveyor 6. The centrifugal washing-classification dehydrator 3 consists of a dehydrating cylinder 7 which is horizontally provided in a housing, a blower 8 connected to the terminal opening end 71 of the dehydrating cylinder 7, and a centrifugal dehydrating disk 9 which is provided in opposition to the leading opening part 72 of the dehydrating cylinder 7 and is provided with washing and classifying functions, and the secondary chute 10, a product chute 11, and a waste chute 12 which are furnished at the lower part.

Description

[Detailed Description of the Invention] (3) Purpose of the Invention The present invention is a method and device for removing salt from sea sand,
Used when sea sand is used as aggregate for reinforced concrete structures.

Conventional technology In recent years, sea sand has been widely used as aggregate for reinforced concrete structures, but due to the action of salt contained in sea sand,
Accidents such as cracks, expansion, and collapse of structures occur one after another.
This has become a major social problem, and urgent measures are currently desired.

Until now, there were only primitive methods to remove salt from sea sand, such as simply pouring water on it in the shower,
The immersion method is used to remove salt by soaking sea sand in a water tank.

(1 and 1) Both of the above methods require a large amount of water (1 to 3 parts of water per liter of raw material), but since they are batch processes (2), there is a lot of variation in the product, and there is always a It is impossible to keep the salt content of sea sand within the standard range of the Japan Society of Civil Engineers and Architects (salt content 0.04% or less).

In addition, the conventional method uses a batch processing method, which results in poor salt removal efficiency.

Constituent rules of the invention ■ ′ -1 The present invention adds a predetermined amount of fresh water to drained seawater and stirs it to remove the salt that is resistant to sea sand and the salt that exists between the grains of sea sand. The seawater is dissolved in fresh water, and the raw material after stirring is supplied by pneumatic transportation to a centrifugal washing/classifying/dehydrating machine equipped with a centrifugal dehydrating disk that has washing and classification functions.The centrifugal washing/classifying/dehydrating machine separates sand and water. The salt content is 0.0 compared to sea sand.
The goal is to continuously obtain 4% or less sand.

Actual 1 (ffl) In Figures 1 to 3, (1) is the raw material hopper,
The raw material, namely drained sea sand, is conveyed into this raw material hopper (1) by suitable means. (2) is an agitator, for example, a sufu conveyor (3) is built into the main body, and inside this main body, sea sand is continuously supplied from a raw material hopper, and sea sand is continuously supplied through a hose, etc. Stir a fixed amount (5-20%) of fresh water,
The stirred material is sent to the next step. That is, in this stirring step, the salt that has adhered to the sea sand and the salt that remains between the particles of the sea sand are dissolved in the fresh water. (3) is a centrifugal washing, classifying and dehydrating machine for separating the raw material taken out from the stirrer (2) into sand and water containing salt.

Sea sand in the raw material hopper (1) is taken out in appropriate amounts by a vibrating feeder (4), and transferred to the first belt conveyor (5).
It is continuously sent to the next step, the stirrer (2). In addition, the raw material taken out from the stirrer (2) is 5 to 20%
This raw material is sent to the second belt conveyor (6) for the next process of centrifugal washing, classification and dehydration* (3).
).

As shown in Figure 4, the centrifugal washer, classification, and dehydrator (3) consists of a dehydration cylinder (7) installed horizontally inside the housing, and a dehydration m (
7) The blower (8) connected (4) to the rear end opening (71) and the tip opening (
A centrifugal dehydration disk (9) with a washing and classification function is installed opposite the 72) and a secondary sheet (10
), product shoe) (11) and discharge shoe 1-
(12), and a plurality of dehydration notches (73) are provided on the bottom of the dehydration cylinder (7), and
There is a supply hopper (near the rear end) into which the raw materials after stirring are carried.
13), and the raw material after stirring is delivered to the supply hopper (1
3) into the dewatering cylinder (7).

Feed hopper (1) by the second heating container (6)
3) The raw material brought into the chamber is a mixture of sand and water containing salt (about 5 to 20% moisture), and this raw material is sent from a supply horn (13) to a blower (8), such as a high-pressure turbo fan. For example, a wind speed of 35 m/s sent by
It is pneumatically transported through the dehydration cylinder (7) by the EC air.

During transportation in the dehydration cylinder (7), some of the water containing salt and fine particles are dehydrated or desilted through a plurality of dehydration notches (73) provided on the bottom of the dehydration cylinder (7), and ) Ejected from the next shade 1 (10). To explain this effect in detail, when the raw material being pneumatically transported in the dehydration cylinder (7) comes into contact with the inner wall surface of the dehydration cylinder (7), the particle velocity in this area is reduced by frictional resistance and moisture adhesion. The speed becomes slower.

However, even if relatively large particles come into contact with the wall surface, the force of blowing them away due to the wind speed overcomes the force and causes them to fall into the dehydration notch (73).
The dehydrator (7) is not drained from the i! Pass. The relatively fine particles are sufficiently wet, so when they come into contact with the inside of the dehydrator # (7), they remain attached to the wall and slowly move along with the water along the inner surface of the dehydrator # (7), and along the way, It is discharged from the dewatering notch (73) to the secondary shoe (10).

The raw material that has passed through the dewatering cylinder (7) in the above manner is centrifuged in front of it, rotating at a high speed of about 800 rpm, for example! It collides with the collision plate (91) at the bottom of 1i (9), and as a result of the collision, it is uniformly scattered into the surrounding dehydration cylinder (92). Due to the impact at this time, some of the particles are directly removed from the dehydrator (92).
Do not use the mechanism (6), the product shoe) (11) will pop out due to repulsive force. After the remaining portion is separated into granules and mud by the impact of the collision, it passes through a dewatering capacity (92) with slits, where it is reliably separated into granules and mud, and each is sent to the product chute. (
11) and the waste chute (12). The products discharged from the product chute (11) are collected in the product storage area by the third belt conveyor (18), and the discharges taken out from the discharge chute (11) and the secondary chute (IO) are discharged. transported to the device.

In addition, the appropriate moisture content for processing raw materials is 5 to 20%.
However, depending on the particle size distribution of raw materials, the particle size required by the product,
It varies depending on the moisture requirement of the final product. Further, even if the moisture content of the raw material is quite high, about 50%, it can be dehydrated (desilted) and the moisture content after dewatering (desilting) can be lowered to about 2%. Power is required to drive the blower and a motor for the centrifugal dewatering disk.

The present invention measures the salinity (7) concentration of water discharged during desalination work, adjusts the amount of water supplied during stirring according to the measured salinity concentration, and adjusts the salt content of the product to produce a product with a uniform salt content. It is also possible to obtain

Figure 5 shows an example of this, in which a salt concentration detection sensor (14) is installed with a salt content adjustment device in the discharge shade 1- (12).
, a controller (15) with a built-in arithmetic unit, and a plurality of solenoid valves (17) provided in each of the plurality of water supply pipes (16) (
or a water flow control valve with a pilot motor), the sensor output is calculated by the calculation device of the meter controller (15), and the number of solenoid valves (17) to be opened (or the opening degree of the control valve) is adjusted using the output. Then, the water supply amount is automatically controlled so that the output of the sensor (14) approaches a constant value. However, a separate circuit is used to constantly spray the minimum necessary amount of water from the water supply pipe.

Back 1 u Centrifugal dehydrator without salt content adjustment device using San'in beach sand as raw material, raw material supply amount: 14T/H1 dehydration basket slit: 0.8 cm, wind speed: 35 m/sec, dewatering rotation speed: 800 rpm As a result, the moisture content (8) and particle size distribution of the raw material were as shown in the following table.

From the table above, the raw material moisture content was 8.6%, and the product moisture content was 2.9%. In addition, the particle size distribution expressed as cumulative particle size is the 6th particle size distribution.
As shown in the figure, it is possible to classify fine particles quite effectively, demonstrating excellent performance as a classifier. Further, the experimental results regarding dehydration are as shown in FIG. 7, and it can be seen that dehydration is performed relatively stably. Also, the 8th
From the figure, it can be seen that even if the moisture content of the raw materials fluctuates, the moisture content of the product (9) remains approximately within 2 to 3%.

This means that it can be used as a fine aggregate for concrete. Furthermore, as shown in Fig. 9, it is clear that the present invention is effective in improving the fine aggregate portion (generally expressed as a percentage of the whole -74μ), and the effect is particularly remarkable when the moisture content is 20%. .

C1 Effects of the Invention According to the present invention, cleaning, classification, and dehydration of products can be performed simultaneously. In addition, effective salt removal is possible with a small amount of water, and sand whose salt content falls within the standard range of the Japan Society of Civil Engineers and Architects can be obtained at low cost. Furthermore, the range of particle sizes that can be processed is relatively wide. Furthermore, according to the present invention, fine powder and mud can be effectively separated with considerably less water, and the mechanism, operation and installation are simple, and the running cost is low.

[Brief explanation of drawings]

Figure 1 is a plan view of the apparatus of the present invention, Figure 2 is a front view of the apparatus without a dehydrator, Figure 3 is a front view of the apparatus without a sea sand hoover (10), and Figure 4 is a front view of the apparatus without a dehydrator. Figure 5 is an explanatory diagram of the main parts of the machine, Figure 5 is an explanatory diagram of the salt content adjustment device, Figures 6 to 9 are diagrams showing the experimental results, Figure 6 is a diagram showing the particle distribution in terms of cumulative particle size, Figure 7 is a diagram showing the moisture content before and after treatment, Figure 8 is a diagram showing the 11 moisture results of fine aggregate,
FIG. 9 is a drawing showing the cleaning performance of fine aggregate.

Claims (1)

[Claims] (1) Add a predetermined amount of fresh water to the drained sea sand and stir it to remove the salt that has adhered to the sea sand and the sea water remaining between the grains of the sea sand. The sea sand after being dissolved in fresh water and stirred is separated into salt-containing water and sand using centrifugal washing, classification and dehydration means to obtain sand with a salt content of 0.04% or less. A distinctive sea sand removal method. (2) A raw material hopper that stores the drained sea sand, an agitator that adds a predetermined amount of fresh water to the sea sand and stirs it, and a centrifugal dewatering device that pneumatically transports the sea sand after the agitation and has washing and classification functions. It consists of a centrifugal washer, classifier, and dehydrator that separates sand and water using disks.The raw material hopper, stirrer, and centrifugal, washer, classifier, and dehydrator are connected by a belt conveyor to continuously process sand with a salt content of 0.04% or less. A sea sand desalting device characterized by being made as described above. (1)