KR100541776B1 - Manufacturing method of artificial zeolite from fly ash - Google Patents

Abstract

The present invention sanitizes a high quality zeolite that can be used as a soil improver, ammonia for sewage and wastewater treatment, a heavy metal ion remover, and a carrier using fly ash generated from a coal-fired power plant. It aims to suggest a safe artificial manufacturing method.

To this end, hydrochloric acid (HCl) is injected while heating anhydrous amorphous aluminum silicate salt, which is produced after combustion, in a coal-fired thermal power plant at 90-180 ° C in aqueous solution. When the pH is 4, the primary conversion to an allophane clay mineral, which is an aluminum silicate salt of amorphous water, is carried out by dehydration and washing with an acid soluble (water-soluble) harmful heavy metal substance. After removal, add an aqueous alkali solution such as sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca (OH) ₂ ), sodium carbonate (Na ₂ CO ₃ ), and potassium carbonate (K ₂ CO ₃ ). Heat stirring at ˜180 ° C. makes the sanitary safe and high yield of artificial zeolite.

Specifically, zeolite has a high cation exchange capacity (CEC), so it has excellent adsorption capacity of cations such as nitrogen and heavy metals, and plays a role in supporting the growth of microorganisms. Therefore, it is expected to be used as a purpose of removing nitrogen and heavy metals in wastewater and wastewater treatment, and as a carrier, and also having excellent retention effect and excellent soil improvement effect.

Fly ash, zeolite, aluminum silicate, cation exchange capacity, soil improver, nitrogen and heavy metal remover

Description

Manufacturing method of artificial zeolite from fly ash

The present invention removes harmful heavy metals from fly ash generated from coal-fired power plants or steel mills, and then artificial zeolites that can be used in nitrogen and heavy metal removers, microbial carriers, and soil improvers in sewage and wastewater. It relates to a method of manufacturing).

Fly ash is a non-combustible clay mineral that is not combustible when coal is burned (1,400 ~ 1,700 ℃) in a coal-fired power plant or steel mill. ) Is recovered as heat is collected and collected by the electrostatic precipitator in the form of fine spherical particles, and discharged. About 70wt% of silicic acid (SiO ₂ ) and alumina (Alumina; Al ₂ O ₃ ) and iron oxide (Fe ₂ O ₃₎ ) Is composed of about 5wt%, other MnO ₂ , TiO ₂ , P ₂ O _5, etc., and anhydrous non-crystalline aluminosilicate as the initial state of the volcanic eruption is the main component.

When the coal ash is heated at weak acidity (pH = 4 to 6), allophane, an amorphous aluminum silicate salt of Hwasu, is produced. Imogolite, a crystalline aluminum silicate salt of Hwasu water with high anion exchange capacity (AEC), is produced, and zeolite (CEC) with high cation exchange capacity (CEC) is obtained when heated in an alkaline state. Zeolite is produced.

Allerpine clay clays are mainly composed of silicon (Si), aluminum (Al), oxygen (O), and hydrogen (H) chemically with a number of Si-O-Al bonds. And clay minerals of aluminum silicate salts, in which the silicic acid is condensed (dehydratedly bonded) to the Al (OH) H ₂ O group of activated aluminum. The hollow spherical particles of amorphous do not have a certain form and are amorphous because silicon, aluminum, oxygen, and hydrogen are randomly combined and appear to be amorphous by X-ray diffraction. Also called clay.

Natural allergenic clay minerals contain a large amount of active aluminum and other active minerals, so they have a high anion exchange capacity (AEC), which is excellent in fixing phosphates. It exists as a large amount of humus soil, and also has a Cation exchange capacity (CEC), so it also has the ability to fix cations such as K ⁺ , Na ⁺ , and NH ₄ ⁺ .

Natural zeolites are minerals that are crystalline aluminum silicate hydrates of alkali and alkaline earth metals, but they are common in many types but have a high water content, crystal properties, and acid phase. Or it is white translucent, and it is called zeolite because it boils and expands when it is heated by blowing pipe. Most kinds are melted in hydrochloric acid (HCl), so it is often glued, but few kinds are insoluble in hydrochloric acid. The main varieties include: Analcime, Apophyllite, Cabbazite, Natrolite, Helandite, Stilbite, Laumontite. ) And Inesite, which are produced in the cavity of a basic igneous rock such as basalt or whirlwind, or in a hot pole. It exists as a secondary mineral in granite and gneiss, and is also produced in mineral veins such as gold mine veins. The crystal structure of each atom is loose and therebetween. Molecular sieve that separates particulates of different sizes by using this property to adsorb other particulate matters. Also used as).

Coal ash is amorphous aluminum silicate anhydrous. Allergy is amorphous aluminum silicate silicate. The difference is that coal ash is anhydrous, whereas allergy is an anhydrous substance.

When allerphan is reacted with alkali, it is crystallized and converted to zeolite. Anhydrous coal ash is also converted to zeolite as it is crystallized when reacted with alkali.

By using the above-described production principle of zeolite, Korean Patent Publication Nos. 1998-033471, 1999-0065036 and Japanese Patent Publication Nos. 59-86687, 6-6314, and 6 -144829, Pyeong 6-340417, Pyeong 7-196315, Pyeong 7-232913, Pyeong 9-255324, 2000-72435, 2001-106523, In 2001-146417 and 2001-220132, a method of producing artificial zeolite by alkali treatment of coal ash has been proposed. However, most of the coal-soluble ash contains a large amount of water-soluble minerals activated by the combustion of minerals. There are also harmful heavy metals such as (Cu), cadmium (Cd), and chromium (Cr). When the products without these harmful heavy metals are used as soil improving agents, the harmful heavy metals are introduced to the human body by the food chain. It is widely reported that the problem of harmful action has been suggested. I'm not in a hurry.
In the process of manufacturing artificial allergy from coal ash and incineration ash of Korean Patent Publication No. 2000-0012888, when adjusting the pH to 2-4 with carbonic acid (H ₂ CO ₃ ) or sulfuric acid, When the heavy metal component (including carbonic acid or sulfate) is generated and the heavy metal component is not sufficiently removed when dehydrated and washed with water, there is a problem in that the product contains high harmful heavy metal in the product when the zeolite is prepared using this allergy.

It is an object of the present invention to remove the harmful heavy metal components contained in coal ash in order to solve the above problems, and then to provide a method for producing artificial zeolite which is hygienically safe and has a high reaction yield.

In order to achieve the above object, the present invention is to change the pH to 4 by adding hydrochloric acid (HCl) in a heated state of coal ash, and then washed with water and dehydrated to remove harmful heavy metal components, and then injected with alkaline aqueous solution. The present invention provides a method for preparing artificial zeolite that is hygienically safe by stirring.

Alkaline clay minerals, which are aluminum silicate salts of amorphous water, are subjected to agitation in the state of heating (90-180 ° C) by adding hydrochloric acid (HCl) while heating the coal ash to 90 ° C in an alkaline aqueous solution. After dehydration, it is sent to a dehydrator, and when dehydrated, it is washed with water to remove water-soluble harmful heavy metals and make a hygienically safe product.

Alkaline metal oxides (Na ₂ O, K ₂ O, etc.) and alkaline earth metal oxides (CaO, MgO, etc.) are present in the coal ash, so the pH is 12-13 in aqueous solution. Then, hydrochloric acid (HCl) is added to adjust the pH to 4, followed by stirring for at least 4 hours while heating to 90-180 ° C. to convert to allerpineic clay mineral, an amorphous aluminum silicate salt.

When the reaction is completed with an allerpine clay clay, it is sent to a dehydrator for dehydration, and the water is washed with an allerpine clay clay dehydrated with a spray nozzle to remove water-soluble harmful heavy metals.

Alkaline metal salts (NaCl, Na ₂ SO ₄ , KCl, K ₂ SO _4, etc.) or alkaline earth metal salts (MgCl ₂ , MgSO ₄ , CaCl _2, etc.) ) And 0.1 to 0.5 N caustic soda (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca (OH) ₂ ), sodium carbonate (Na ₂ CO ₃ ), potassium carbonate (K ₂ CO ₃ ) alone or two types Alkali aqueous solution mixed with the above was added, and the mixture was stirred for 4 hours or more while heated to 90-180 占 폚 to convert to zeolite.

When the reaction is completed with zeolite, it is dehydrated and washed with water and then dried to produce a powder, or a binder is mixed and molded into spherical or granular pellets and dried to produce a product.

If necessary, neutralize the pH to 7, and then process the product into the required form to produce a product.

Molding process in pellet form is 5% by weight of bentonite as inorganic binder and 5% by weight of zeolite based on the weight of zeolite to zeolite which has been removed harmful metals and dehydrated, and soda (Alginic acid) soda as organic binder. 10% by weight of cellulose (Cellulose), 10% by weight of ammonium chloride (NH ₄ Cl) is added to the water to facilitate the molding process in pellet form, water content of the mixture is 38 ~ 43wt% After mixing, stirring and mixing, forming into spherical or rod-shaped pellets, drying them naturally at room temperature, and heating them to at least 1,000 ℃ in an electric furnace or a heating furnace, and drying the porous Process the pellets.

The dehydration liquid and the flushing water containing the harmful heavy metal components are sent to the neutralization tank to adjust the pH to 7-8 with a neutralizing agent to convert the water-soluble heavy metal components into solid metal hydroxides, and then to the flocculation tank to facilitate the sedimentation and separation in the precipitation tank. Inject the adjuvant to form a floc, and then send it to the settling tank to precipitate solids, and the supernatant is sent to a treatment tank for reuse or discharge as washing water, and the precipitated slurry is sent to a dehydrator for dehydration.

As will be apparent from the above description, the present invention has the effect of recycling the waste resources by itself to make coal ash generated as a waste of oil price zeolite, and to remove nitrogen and heavy metals in sewage and wastewater treatment and to support microorganisms. It can be used as a sieve, and in the agricultural field is expected to be widely used in these fields because of its excellent efficacy when used as a soil improving agent.

Claims (2)

In order to remove harmful water-soluble heavy metal components in the production of zeolite from fly ash, hydrochloric acid (HCl) was added and the pH was adjusted to 4 while stirring for at least 4 hours to obtain amorphous aluminum silicate salt. After conversion to an allergenic clay mineral, the detrimental heavy metals were removed by dehydration and washing, and then salts of alkali metals (NaCl, Na ₂ SO ₄ , KCl, K ₂ SO ₄ ) or salts of alkaline earth metals (MgCl ₂ , MgSO ₄ , CaCl ₂ ) and 0.1 ~ 0.5N Caustic Sodium (NaOH) or Potassium Hydroxide (KOH), Calcium Hydroxide (Ca (OH) ₂ ), Sodium Carbonate (Na ₂ CO ₃ ), Potassium Carbonate (K ₂ CO ₃ ) Method of preparing an artificial zeolite by adding an aqueous alkali solution mixed with one or two or more of them and stirring the mixture for at least 4 hours while heating to 90 to 180 ° C., followed by dehydration and washing with water. According to claim 1, 5 wt% of bentonite in an inorganic binder (Binder) based on the weight of the zeolite in the dehydrated powder artificial zeolite, Alginic acid soda (Soda) or cellulose as an organic binder 10 wt% of the (Cellulose) system is mixed, and 10 wt% of ammonium chloride (NH ₄ Cl) is mixed therein, and water is added to them to facilitate the molding process into pellets. After adjusting to 43wt%, the mixture is stirred and mixed, then formed into spherical or rod-shaped pellets and dried naturally at room temperature, and then heated to 1,000 ° C or above in an electric furnace or a heating furnace to be porous. To prepare artificial zeolite on dried pellets)