JPS5940508B2 - Separation method for suspended particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for separating microparticles from a dispersed suspension of ferromagnetic or paramagnetic microparticles.

Conventionally, precoat filtration methods and centrifugation methods have been mainly used to separate the above-mentioned fine particles, and recently a magnetic separation method using superconducting magnets using steel wool with a diameter of about 10 μm has been proposed. The method has the following drawbacks:

First, regarding the filtration method, if a large amount of suspension is to be processed, large equipment or a long time is required.

When the particle size of the fine particles is approximately several +λ, filtration cannot be carried out because there is no suitable filter material to filter the fine particles.

Furthermore, the filter medium becomes clogged during filtration, making maintenance difficult.

Regarding the centrifugal separation method, in the dehydration type that uses a filter material, as with the filtration method, when the particle size becomes about several + λ, there is no suitable filter material.
There are drawbacks such as clogging of the filter media and troublesome maintenance.

On the other hand, in the decanter type centrifugal separation method, the processing speed becomes low when sufficient separation is attempted, and the processing speed becomes significantly low when the particle size becomes approximately several +λ.

Therefore, it is unsuitable for processing large amounts of suspension.

Regarding the third magnetic separation method using steel wool, it is still difficult to separate fine particles with a particle size of several +λ.

An object of the present invention is to continuously separate and remove ferromagnetic or paramagnetic fine particles having a particle size of about +λ.

The main application of the present invention is to remove harmful substances in water such as phosphorus and sulfur by dispersing ferromagnetic and paramagnetic fine particles in water as a scavenger to form a suspension. This is a process in which the dispersed fine particles are separated from the liquid when removal is carried out by a method of adsorbing harmful metals in water or a method of incorporating harmful metals into fine particles.

In the present invention, when separating and removing ferromagnetic particles or paramagnetic particles adsorbing or containing inorganic and organic substances from a suspension, ferromagnetic particles are dispersed in the suspension,
This method of separating fine particles is characterized in that the fine particles are introduced into a magnetic field, the fine particles are magnetically attached to the ferromagnetic particles, and then the fine particles are removed from the liquid together with the ferromagnetic particles.

To be more specific, it is impossible to separate ferromagnetic or paramagnetic particles with particle diameters of several + λ as they are by magnetic separation using conventional methods, but particles with particle sizes of several hundred λ to several thousand λ are added to a suspension in advance. If human ferromagnetic particles are added and introduced into a magnetic field, the magnetization of the ferromagnetic particles will be saturated, and a magnetic field of about the Ms (saturation magnetization) of the particles will be created near the particles, and the range of that magnetic field will be Since the particle size is about that size, an extremely large magnetic field gradient is obtained, and the fine particles are attracted and adhered to the ferromagnetic particles.

The ferromagnetic particles with fine particles attached thereto are subsequently collected by another separation device and removed from the system.

For separation at this stage, centrifugation, sedimentation, magnetic separation using steel wool, etc. can be used.

The main point of the present invention is to add ferromagnetic particles to a suspension and make them adhere to the suspension, and a similar method to this method is a filter-like filter filled with ferromagnetic particles in a magnetic field. The scope of the present invention includes a method in which a plate, membrane, or fiber in which ferromagnetic particles are embedded is provided and a suspension is passed through the plate, membrane, or fiber.

The present invention will be specifically explained below using Examples.

Example 1 A suspension of δ-Fe00H (ferrimagnetic) particles having an average particle size of 50 particles dispersed in water at a concentration of 0.19/13 was separated using the magnetic separation device shown in the figure.

In the figure, 1 is an air-core coil capable of generating a magnetic field of 20,000 e, 2 is a pipe through which the suspension flows, and 3 is steel wool.

When the suspension was directly passed through this separation device, the concentration of the suspension in the effluent was 0.099/13.

On the other hand, when magnetite particles with an average particle size of 0.1μ were added to the suspension at a concentration of 1 g/l and similar magnetic separation was performed, the concentration of the suspended matter in the effluent was 0.02 g/l. Ta.

Example 2 Ferrous ion Fe2+ in water containing 1 oppmfi of mercury,
Add ferric ion Fe3+ in a ratio of l:2,
Furthermore, an alkali was added and the mixture was stirred at room temperature to obtain fine particles of magnetite.

The amount of mercury in the solution after the reaction is less than 0.01 ppnm,
Mercury is incorporated and contained within the crystal lattice of magnetite.

The average particle diameter of the produced magnetite fine particles was 100λ or less.

A suspension of magnetite fine particles was separated using the magnetic separator used in Example 1 in one phase.

The amount of magnetite in the original suspension was 500 ppIll, while the amount of magnetite in the effluent after the separation operation was 45 ppIll.
0p-, and was hardly separated.

Add 1g of magnetite particles with an average particle size of 0.1μ to the original suspension.
After adding the solution at a concentration of 1/l, a magnetic separation operation was performed, and the total amount of magnetite in the effluent was 40 ppm.

As described in the above examples, the present invention is extremely effective in continuously removing ferromagnetic and paramagnetic fine particles suspended in a liquid.

Note that when using ferromagnetic particles with low saturation magnetization, saturation can be achieved with a lower magnetic field.

[Brief explanation of the drawing]

The figure shows an example of a magnetic separation device used in the present invention, in which 1 is an air-core coil, 2 is a pipe through which a suspension flows, 3 is steel wool, and 4 is a valve for adjusting the flow rate.

Claims (1)

[Claims] 1. A first step of adding ferromagnetic fine particles or paramagnetic fine particles to a liquid containing an inorganic or organic substance so that the substance is adsorbed or contained in the fine particles to form a suspension, and the above suspension. a second step of dispersing magnetic particles having a larger particle size than the ferromagnetic particles or paramagnetic particles; then, the suspension is introduced into a magnetic field, and the ferromagnetic particles are exposed to the magnetic particles; 1. A method for separating suspended fine particles, which comprises the step of removing the ferromagnetic particles from the liquid together with the ferromagnetic particles.