JPS6265940A - Method for desiliconizing aqueous acid iron chloride - Google Patents

Abstract

PURPOSE:To inexpensively and efficiently obtain iron oxide having high purity by feeding air to an aq. acid iron chloride soln. added with a surface active agent and alumina granular particles to foam the soln. and floating and separating the silicon-components in the dissolved state. CONSTITUTION:The surface active agent (e.g.: lauryl pyridinium chloride) and alpha-alumina granular particles as the adsorption assistant are added to the aq. acid iron chloride soln. which is waste liquid of pickling of steel products and after the soln. is stirred, the air is fed thereto for 30min-1hr at 5l/min to foam the soln. The various silicon-components in the dissolved state contained in the aq. soln. are floated and separated. The silicon-components (SiO2) in the aq. acid iron chloride soln. are thereby decreased to <=20ppm.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for removing silicon content from a steel pickling waste solution, and in particular to a method for removing silicon content from a steel pickling waste solution, in particular a method for removing the unsatisfactory dissolved T18 state contained in a steel pickling waste solution. The present invention relates to a method for removing silicon content containing iron chloride and obtaining a melt containing iron chloride as a main component, which can be used for manufacturing high-purity products such as ferrite iron oxide.

[Prior Art] As a method for removing silicon contained in the waste solution from hydrochloric acid pickling of steel materials, attempts have been made to use polymer flocculants or ultra-superfluid flow, but these methods have failed in the reaction region (PH < 1). ) The ability to remove silicon from the waste liquid was low, and it was impossible to reduce the silicon content to less than 20.0 ppm.

[Problem that the invention seeks to solve]

Silicon contained in the waste solution from hydrochloric acid pickling of steel materials exists in various states such as silicic acid, silicic acid dimer, and colloidal silicic acid.
There are limits to methods such as ultrafiltration that separate particles based on differences in particle size.

In addition, in the existing method of adding a cationic polyacrylamide-based polymer flocculant to flocculate and separate silica compounds in waste acid by filtration, (1) a filtration operation is required; (2) f! I! strong waste acid (lfl=-1~0.
5) Under these conditions, the desiliconization efficiency is as low as 5 to 10%. (3) The above flocculant t-310□ The weight ratio is 0.0 with respect to the converted amount.
Even if 0.2 or more is added to 4, 510
□ only increased to about 180 to 250 ppm.

There are drawbacks such as.

However, iron oxide for ferrite (1) 1 Seed crystal SiO
□Content is 100 ppm or less (JIS K 1462
However, since it is difficult to obtain iron oxide of stable quality using the existing methods mentioned above, it was necessary to establish an inexpensive and efficient method for removing silicon.

The present invention aims to provide a desiliconization method for steel material pickling waste fluid that meets the above-mentioned needs.

[Means to solve all problems]

The bubble separation method, in which all the ions, molecules, colloids, and precipitates in a solution float to the liquid surface using bubbles, is generally well known as a flotation method and a concentration separation method for analyzing trace metals in water. The present invention was completed after studying the types of surfactants, the effects of adsorption aids, etc. in order to apply this method to the removal of silica compounds from waste acids.

That is, in the present invention, a surfactant and alumina powder are completely added to an acidic iron chloride aqueous solution, air is introduced to form bubbles, and the water Fjff1. This is a method for desiliconizing an acidic iron chloride aqueous solution, which is characterized by flotation-separation of the silicon content in the atomic state contained therein.

[Effect]

The form of silica in waste acid is not clear, but based on literature and its behavior in waste acid, Si(OH)4 and H2S1205°H25
It is thought that it exists as ionic monomers, nonionic monomers, hydrosils, etc. such as 1, O, ·H2SiO3.

Furthermore, these silica compounds are thought to exist in solution or as ultrafine particles, and cannot be filtered or separated using a Millipore filter with a pore size of 0.45 microns or a commercially available ultrafilter with a molecular weight fraction of 5,000.

However, since these dissolved silicas gradually decrease over time in the waste acid, it is thought that insolubilization is progressing due to polymerization or adhesion to vessel walls or suspended substances.

Based on the above phenomenon and the presumed mechanism, a method can be considered in which a surfactant or adsorption aid having an opposite charge to the silica compound is added, gas is blown into the silica compound, and a large number of bubbles are generated to float and separate the silica compound.

In this case, the separation efficiency is considered to be influenced by the voice of the solution, the presence or absence of surfactants and adsorption aids, their type, addition method, bubble condition, etc.

However, the waste acid usually contains 0.1-1 Kmoz/m of free acid and 1% 2.8 K no, 1 p/m of I? Since it contains eC12, a large amount of alkali is required to raise and adjust the pH, and addition of alkali tends to cause a decrease in yield and quality of recovered hydrochloric acid.

Therefore, by adding a small amount of third substance, high desiliconization efficiency ti
Anionic surfactants such as dodecylamine, 2-ethylhexyl sodium sulfosuccinate, and sodium dodecyl sulfate; cationic surfactants such as alkylpyridium chloride and alkylammonium chloride;
Nonionic surfactants such as polyoxyethylene alkyl ethers and alkylphenyl ethers, or amphoteric surfactants such as dodecyl betaine, each alone, and various combinations of the above anionic, cationic, nonionic, and amphoteric surfactants, or TiO2, α-A/2 as adsorption aid
03. γ-A/203°Aj O+ZrO2, AI! I
20. +TiO2, Ti, etc. were all added and tested.

As a result, the desiliconization efficiency in the case of using surfactant alone is better in the order of cationic, nonionic, amphoteric, and anionic, with a maximum of 81% when the dissolved state is 510,246 to 57 ppm, respectively.
They were 80%, 74%, and 56%. In addition, when two of the above-mentioned different types of surfactants were mixed, the desiliconization efficiency was slightly improved in both cases compared to when they were used alone.

In addition, as a result of experiments with each of the above substances as adsorption aids, we have found that alumina powder is the most effective when used in combination with the above surfactant. Alumina is usually used as an adsorption aid, but Aj(OH), (such as boehmite)
γ-alumina is a metastable alumina produced by the low-temperature (500-550°C) thermal decomposition of
+ produces m. At in the waste acid is not preferable because it becomes an impurity in the nftoferite and completely reduces the quality of the product.

On the other hand, a-alumina, such as γ-alumina, has a higher temperature (1
Calcined and stabilized at 000 to 1100°C, its activity and specific surface area are inferior to r-alumina, but A/
Since there is no elution of alumina, the quality of the recovered ferrite does not deteriorate.Therefore, in the present invention, it is recommended to use a-alumina as the alumina powder.

However, when the adsorption aid was added to the waste acid in advance, the surfactant was added after stirring, and all foam separation was carried out, the desiliconization efficiency was dramatically improved.

In addition, air blowing conditions are generally 5 to 5001 /
min, time is about 60 minutes to 1 hour.

Below are some example measurements.

In the following examples, the air blowing conditions were 100/min,
When the surfactant was used alone, the mixture was stirred for 30 minutes, and when the alumina powder was used in combination with the powder, the mixture was stirred for 10 minutes by blowing in nitrogen gas, and then aerated at the same flow rate for an additional 50 minutes after adding the surfactant.

Example 1 α~Alumina powder (20ppm 0) Ten-cationic surfactant Example 2 α-Alumina powder (20ppm) Ten Nonionic surfactant Example 3 α-Alumina powder (20ppm) + Anionic "Surfactant" Example 4 α-Alumina powder (20 ppm) Ampholytic surfactant By separating 2
It becomes possible to reduce the amount to 0 ppfll or less, and high-quality iron oxide can be recovered by calcining this waste acid.

Sub-agent: 1) Akira Sub-agent Ryo Hagi Hara - Sub-agent Atsuo Yasunishi

Claims (1)

[Claims] The method is characterized in that a surfactant and alumina powder are added to an acidic iron chloride aqueous solution, air is introduced to form bubbles, and silicon components in various dissolved states contained in the aqueous solution are floated and separated. A method for desiliconizing an acidic iron chloride aqueous solution.