TWI425975B - A method of treating a fluorine-containing fluid with a metal-containing substance - Google Patents

Description

Method for treating a fluorine-containing fluid with a metal-containing substance

This invention relates to a process for treating a fluorine-containing fluid, and more particularly to a process for treating a fluorine-containing fluid with a metal-containing material.

The main sources of fluorine-containing wastewater are semiconductor manufacturing, wire and cable industry, glass manufacturing, steel industry, electroplating industry, fluoride manufacturing, aluminum plate printing industry, ceramic industry and phosphate fertilizer, rocket raw materials, pesticides, soap, toothpaste. , electronic components manufacturing and optoelectronics. Among them, the semiconductor manufacturing industry and the photovoltaic industry are the fastest-growing high-tech industries, producing a lot of pollution, among which fluoride ion is one of the most environmentally harmful harmful substances. At present, fluorine-containing wastewater is most often treated with an excess of calcium-based chemical coagulant to remove fluorine to produce sludge, but the cost of disposal of the medicament and sludge is quite expensive.

On the other hand, in the process of manufacturing primary aluminum ingots, the domestic scrap aluminum smelting industry needs to add many kinds of metals to meet the specifications to prepare the required concentration. Therefore, the dust collecting fly ash and aluminum slag generated in the process contain a small amount of various kinds. The heavy metal components, which are tested by the toxic dissolution test procedure (TCLP), may be attributed to hazardous industrial waste. If this is the case, it is necessary to carry out the landfill control operation after the curing process, which is a very important burden for the operators.

Waste aluminum smelting aluminum slag and fly ash have the potential to be reused after recycling, such as treatment techniques such as stabilization, production of alum, electrostatic recovery of aluminum, washing, pickling, caustic washing or sorting, but Most of them are still technologies that have not been fully resourced, and most of them fail to consider the removal of heavy metals at the same time. Of course, there is no need to consider the technology for treating fluorine-containing wastewater at the same time.

Furthermore, the slag by-product produced by the domestic electric arc furnace steelmaking process is as high as 1 million tons per year. Since the steelmaking source contains iron ore, scrap steel, aluminum ingot, lanthanum ferromanganese, slag forming agent, coke, limestone, etc., The slag composition is rich in metals such as iron, aluminum, magnesium, calcium, etc., and the average content of the main content is about Fe ₂ O ₃ >CaO>SiO ₂ >Al ₂ O ₃ >MgO>MnO. Although the slag can be applied to paving and other projects after magnetic separation, crushing, sieving, etc., there are still doubts about environmental pollution such as slag foaming and metal release. Of course, there is no technology for considering the treatment of fluorine-containing wastewater. check.

Accordingly, it is an object of the present invention to provide a method of treating a fluorine-containing fluid with a metal-containing material that can simultaneously treat waste from both processes.

Thus, the present invention comprises a method of treating a fluorine-containing fluid with a metal-containing material, comprising a mixing step, and a reaction step. The mixing step is to mix the metal-containing material with the fluorine-containing fluid in a predetermined ratio, and the reaction step is to control the appropriate reaction conditions to react the metal-containing material with the fluorine-containing fluid to form the metal fluoride.

The effect of the invention is that, by the above treatment method, in addition to the simultaneous treatment of the waste of the two processes, the fluorine content in the fluorine-containing fluid can be rapidly reduced, and a stable metal fluoride is formed, which can simplify the waste disposal process. And reduce processing costs.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments.

Referring to Figure 1, a preferred embodiment of a method of treating a fluorine-containing fluid with a metal-containing material of the present invention comprises a mixing step 21 and a reaction step 22. The mixing step 21 is to mix the metal-containing material with the fluorine-containing fluid in a predetermined ratio, and the reaction step 22 is to control the appropriate reaction conditions to react the metal-containing material with the fluorine-containing fluid to form a metal fluoride.

The fluorine-containing fluid may be a gas, a liquid, or a mixture of the two, and the main sources of the fluorine-containing fluid are photovoltaic materials and component manufacturing, semiconductor manufacturing, wire and cable industry, glass manufacturing, steel industry, electroplating. Industry, fluoride manufacturing, aluminum sheet printing, ceramics, phosphate fertilizer, rocket raw materials, pesticides, soap, toothpaste, electronic parts manufacturing and optoelectronics, etc., fluorine-containing fluid components are HF (liquid or gas) or F ₂ (gas) is dominant, and the fluorine concentration may be 1 ppm (gas) or 15 ppm (liquid) or more.

Further, the metal-containing substance may be a metal-containing waste, a dry/wet sludge, a waste liquid, a mineral, or a mixed form of the above. As shown in Table 1 below, it is the item, category, and main metal component of the metal-containing substance. In the present embodiment, the fly ash, the aluminum slag, the slag or the above mixture produced in the process of waste aluminum smelting and steel making are described as an example, but not limited thereto.

Metal (Fe, Al, Mn, Co, Ni, Ag, Cr, Ce, V, Cu, Mo, Pt, etc.) or its oxide (in terms of metal activity, there are many kinds of oxidized metals, and their reactivity is sequential They are: FeOOH>MnO>Co ₃ O ₄ >NiO>Fe ₂ O ₃ >Ag ₂ O>Cr ₂ O ₃ >CeO ₂ >V ₂ O ₅ >CuO>MoO ₃ >SiO ₂ ) and other types of high negative A fluorine ion reaction can produce a metal fluoride. The reaction mechanism of this embodiment can be expressed by the following reaction formula:

F ^- +M ⁿ⁺ →MF _n , where M represents a metal element and n is a valence.

Through the above reaction formula, the fluoride ion in the fluorine-containing fluid can be converted into a metal fluoride complex or solid phase deposition by reacting with the fly ash, aluminum slag or metal in the slag, for example, AlF ₃ , FeF ₃ and CuF ₂ .

Some metals, such as Co, Ni, Cr, Ce and V, are heavy metals declared by the Environmental Protection Agency, so if they are treated as described above, secondary pollution of wastewater can be reduced. While Ag, Pt, and V are precious metals, the cost is relatively expensive, and it is a pity after the reaction. However, due to the low content, the original value is not recovered. If a high amount of conventional metals such as Fe, Al, Mn, and Cu are used as reactants, the cost is lower, and the problem of reprocessing without derivatives is easy to obtain and manufacture. Based on the secondary pollution treatment and cost considerations, the present invention selects a high concentration (800-20000 ppm) fluorine-containing fluid of the factory as a source of fluorine, reacts with aluminum slag or slag, and removes most of the fluorine and some metal substances. .

The operating conditions and results of the present invention are illustrated below by a plurality of experimental examples.

<pre-preparation> (1) Fly ash or aluminum slag or slag collected from the factory, sealed with blunt gas, and tested as follows:

A. Elemental analysis: ICP-MS, XRF, nitrogen oxide analyzer.

B. TCLP analysis of hazardous waste control projects (including EU control projects).

C. Crystal phase (XRD), morphology (SEM), size (SEM, TEM) analysis.

D. Other feature analysis, such as BET, FTIR, TGA.

(2) Separate high-concentration fluorine-containing wastewater from the plant (photovoltaic power plant, HCFC plant) and carry out the following tests:

A. Analysis of fluoride ion concentration.

B. Metal composition analysis: ICP-MS.

C. Other analysis: N, O, Cl content, pH value.

<Experimental Example 1>

Fluoride-containing wastewater was treated with fly ash containing aluminum (30%) with a fluoride ion concentration [F ^- ] = 6800 ppm. Among them, the composition of fly ash is shown in Table 2 below.

(1) Operating conditions

Weight ratio (liquid-solid ratio, LSR): fluorine-containing wastewater/fly ash = 100, 50, 25, and 17.

Reaction time: 60 minutes or less (the above is also possible, but the operating cost is increased).

Operating temperature: room temperature (about 25 ° C).

(2) Processing effect

As shown in Figure 2, when the weight ratio of fluorine-containing wastewater / fly ash = 17, the reaction time is within 15 minutes, the fluoride ion concentration can be reduced to less than 15ppm, the fluoride ion removal rate is 99.8%, and the detailed treatment effect is as follows Table 3 shows.

<Experimental Example 2>

The fluorine-containing wastewater was treated with aluminum slag containing aluminum (80.9%), wherein the fluoride ion concentration [F ^- ] = 6800 ppm; wherein the composition of the aluminum slag is as shown in Table 4 below.

(1) Operating conditions

Weight ratio (liquid-solid ratio, LSR): fluorine-containing wastewater/aluminum slag = 200, 100, and 50.

Reaction time: 60 minutes or less (the above is also possible, but the operating cost is increased).

Operating temperature: room temperature (about 25 ° C).

(2) Processing effect

As shown in Fig. 3, when the weight ratio of fluorine-containing wastewater/aluminum slag is 50, since the aluminum slag particles are larger than the fly ash, the reaction is slow, so when the reaction time is 30 minutes, the fluoride ion concentration is lowered to 15 ppm, and the fluoride ion removal rate is Up to 99.8%. The detailed processing results are shown in Table 5.

<Experimental Example 3>

The hydrofluoric acid-containing gas ([HF] = 2000 ppm) was treated with iron (30%) slag.

(1) Operating conditions

Reaction temperature: 25 ° C ~ 200 ° C.

Reaction residence time: very short, less than 1 second, can also be extended.

Processing time: less than 30 minutes, the processing time can be extended by increasing the iron-containing slag.

Inflow conditions: continuous influx of hydrofluoric acid gas, flow rate = 200 standard cm ³ /min.

The iron-containing slag weighs 1 gram.

(2) Processing effect

As shown in Figure 4, [HF] has a maximum removal rate of 76% (at 25 ° C), 90% (at 115 ° C), and 95% (at 200 ° C), due to the small weight of iron-containing slag, and the gas is Continuous inflow state, so the removal rate of hydrofluoric acid gas decreases rapidly with time. In order to maintain high removal rate of fluorine, the reaction temperature or iron-containing slag weight can be increased, and at a treatment temperature of 115 ° C. The processing efficiency can exceed 85%.

(3) Description of processing effect:

According to China's regulations "Opto-contamination and emission standards for photovoltaic materials and component manufacturing", the emission standard for gaseous pollutants, hydrofluoric acid (HF): the concentration of exhaust gas at the front end of pollution control equipment is more than 3ppm, and the treatment efficiency should be 85%. . It can be seen that the treatment efficiency of the continuously influent hydrofluoric acid fluid at 115 ° C can effectively exceed 85%.

<Experimental Example 4>

The fluorine-containing gas was treated with aluminum (80.9%) aluminum slag ([F ₂ ] = 8000 ppm).

(1) Operating conditions

Reaction temperature: 25 ° C ~ 200 ° C.

Reaction residence time: very short, less than 1 second, can also be extended.

Processing time: less than 30 minutes, the processing time can be extended by increasing the iron-containing slag.

Inflow conditions: continuous inflow of fluorine gas, flow rate = 200 standard cm ³ /min.

The aluminum-containing aluminum slag weighs 1 gram.

(2) Processing effect

As shown in Figure 5, the highest removal rate of fluorine gas can reach 80% (at 25 ° C), 92% (at 115 ° C), 99% (at 200 ° C), because the aluminum-containing aluminum slag weighs very little, and the gas is In the continuous inflow state, the removal rate of the fluorine gas is decremented with time. In order to maintain a high removal rate of fluorine, the reaction temperature or the weight of the aluminum-containing aluminum slag can be increased, and at a treatment temperature of 115 ° C, Processing efficiency can effectively exceed 85%.

It can be seen from the above experimental examples that the present invention can rapidly and greatly reduce the fluorine content in the fluorine-containing fluid by mixing the wastes of the two processes and controlling the appropriate reaction temperature and time by the above treatment method. And generate stable metal fluoride to reduce environmental pollution, in addition to the simultaneous treatment of two processes of waste, but also simplify the waste disposal process and reduce processing costs.

Referring to FIG. 6, if the fluorine-containing fluid is a liquid, the present invention may further comprise a precipitation step 23, after which the coagulant is added to further reduce the suspended matter content in the fluorine-containing fluid, that is, the fluid can be lowered. The turbidity, because the turbidity has a great influence on the discharge water, when the turbidity is increased, the load of the rear filtration equipment will be increased. When the fluorine-containing fluid is a liquid, the suspended solids generated after mixing with fly ash or aluminum slag or slag are sometimes not easy to settle or float, so that the turbidity cannot be lowered, and the discharge solids discharge standard (mostly 30 mg/L) cannot be met. . In the present embodiment, the coagulant is an anionic polymer and is Polyacrylamide Ciba-340, but is not limited thereto.

<Experimental Example 5>

The effect of the settling time after the addition of the coagulant on the turbidity after the reaction of the fly ash with the fluorine-containing liquid, wherein the fluoride ion concentration ([F ^- ]) = 6800 ppm.

(1) Operating conditions

Weight ratio (liquid-solid ratio, LSR): fluorine-containing liquid / fly ash = 17.

Reaction temperature: room temperature (about 25 ° C).

Processing step: After reacting the fluorine-containing liquid with the fly ash for 15 minutes or 30 minutes, 0.1 ml of a coagulant (1 ml) was added, stirred for 1 minute, and allowed to stand, and the turbidity change value within 20 minutes was measured.

(2) Processing effect

As shown in Fig. 7, the fluorine-containing liquid reacted with the fly ash for 15 minutes. At this time, the turbidity exceeded 1000, and the coagulant was added to react, and the turbidity decreased remarkably. After standing for 15 minutes, the turbidity no longer decreased. 76. The fluorine-containing liquid reacted with the fly ash for 30 minutes. At this time, the turbidity exceeded 1000, and then the coagulant was added to react. The turbidity also decreased significantly, and quickly decreased to 65 after standing for 5 minutes, and turbid after about 15 minutes. The degree is no longer reduced, its value is 42, after the measurement, the suspended solids are only 20mg / L, which is already lower than the discharge standard.

In summary, the present invention, by the above treatment method, can simultaneously reduce the waste of the two processes at the same time, rapidly reduce the fluorine content in the fluorine-containing fluid, and generate stable metal fluoride, which can simplify the disposal of waste. The process and the reduction of the processing cost can indeed achieve the object of the present invention.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

21‧‧‧Mixed steps

22‧‧‧Reaction steps

23‧‧‧Precipitation step

Figure 1 is a flow chart illustrating a preferred embodiment of the method of the present invention for treating a fluorine-containing fluid with a metal-containing material;

2 is a graph illustrating changes in fluoride ion content after treatment of fluorine-containing wastewater with aluminum-containing fly ash;

Figure 3 is a graph illustrating changes in fluoride ion content after treatment of fluorine-containing wastewater with aluminum-containing aluminum slag;

Figure 4 is a graph illustrating the removal rate of fluorine after continuous treatment of hydrofluoric acid-containing gas with iron-containing slag at different reaction temperatures;

Figure 5 is a graph illustrating the removal rate of fluorine after continuous treatment of fluorine-containing gas with aluminum-containing aluminum slag at different reaction temperatures;

Figure 6 is a flow chart showing that the embodiment may further comprise a precipitation step;

Figure 7 is a graph showing the effect of the settling time of the addition of the coagulant on the turbidity after the reaction of the fly ash with the fluorine-containing liquid.

twenty one. . . Mixing step

twenty two. . . Reaction step

Claims (7)

A method for treating a fluorine-containing fluid with a metal-containing substance, comprising: a mixing step of mixing a metal-containing substance with a fluorine-containing fluid in a predetermined ratio; and a reaction step of controlling a suitable reaction condition to cause the metal-containing substance to The fluorine-containing fluid reacts with the metal fluoride; wherein the metal-containing material is selected from fly ash, aluminum slag, slag or a mixture of the above, which is produced in the process of waste aluminum smelting and steel making. A method of treating a fluorine-containing fluid with a metal-containing substance according to the first aspect of the invention, wherein the fluorine-containing fluid is a gas. A method of treating a fluorine-containing fluid with a metal-containing substance according to the first aspect of the invention, wherein the fluorine-containing fluid is a liquid. The method of treating a fluorine-containing fluid with a metal-containing substance according to item 3 of the scope of the patent application further comprises a precipitation step of adding a coagulant after the reaction step. A method of treating a fluorine-containing fluid with a metal-containing substance according to the fourth aspect of the patent application, wherein the coagulant is an anionic polymer. A method of treating a fluorine-containing fluid with a metal-containing substance according to any one of claims 1 to 5, wherein the reaction time is less than 3 hours. A method of treating a fluorine-containing fluid with a metal-containing substance according to the sixth aspect of the invention, wherein the reaction temperature is less than 800 °C.