KR100205535B1 - Adsorbent preparation using powdered cokes - Google Patents

Abstract

In the present invention, in the method for preparing an adsorbent using CDQ powder coke, the powder coke generated in the CDQ process is selected to have a particle size of 50-170mesh, and then treated with hydrofluoric acid at a concentration of 15-30%. It relates to a method for producing an adsorbent using a CDQ powder coke, characterized in that the drying step.

Description

Adsorbent Manufacturing Method Using Powder Coke

1 is a view schematically showing the process sequence of the adsorbent production method of the present invention.

2 is a view showing a step of generating powdered coke.

3 is a graph comparing the adsorption capacity of CDQ powder coke when acid treated with hydrofluoric acid and hydrochloric acid.

4 is a graph showing the relationship between the concentration of hydrofluoric acid and the adsorption capacity of the CDQ powder coke.

The present invention relates to a method for producing an adsorbent using powder coke, and more particularly, to prepare an adsorbent for adsorbing and removing environmental pollutants generated in various industrial sites by activating CDQ powder coke generated in a coke plant of an ironworks with hydrofluoric acid. It is about a method.

Activated carbon, which is the most widely used adsorbent for wastewater treatment, is known to generate a large amount of pollutants in its manufacturing plant. This is the raw material used in the manufacturing process of activated carbon, such as wood, coal, and coconut shell, at 1000 ℃. This is due to the large amount of volatile pollutants produced when carbonizing. In addition, the waste adsorbent generated when activated carbon is used in the wastewater treatment process must undergo an incineration process that requires a large amount of energy at the time of treatment. Therefore, when using the existing adsorbents such as activated carbon, a lot of pollutants are discharged during manufacture, incineration (or reprocessing) is required separately when treating the adsorbent, and it is not only expensive to store and transport the waste adsorbent. Because activated carbon itself is expensive, the economic burden is high. For this reason, wastewater treatment using activated charcoal is carried out especially where advanced treatment is required.

An object of the present invention is to solve the above problems and to provide a method for producing an economical adsorbent using CDQ powder coke generated in the coke plant of steel mills. Another object of the present invention is to provide a method for producing an adsorbent free of pollution by recycling waste hydrofluoric acid used to activate CDQ powder coke.

In the present invention, in the method for preparing adsorbent using powder coke, CDQ powder coke is selected to 50-170mesh using standard body, treated with hydrofluoric acid at 15-30% concentration, washed with water and dried sufficiently to produce adsorbent. It relates to a method for producing an adsorbent using CDQ powder coke, characterized in that consisting of steps.

Waste hydrofluoric acid generated in the hydrofluoric acid treatment is recovered by distillation, condensation, and recycled after adjusting to the concentration of 15-30%.

There are three types of powder coke generated in steel mills, namely, those produced during the transport of coke (hereinafter referred to as 'lightfall powder coke'), and those produced by cooling heated coke. (Hereinafter referred to as 'digestion tank coke') and those produced during dry cooling of coke (hereinafter referred to as 'CDQ (Coke Dry Quenching) powder coke'). same.

In FIG. 2, the digester powder coke is quenched by sprinkling water on the coke which has undergone heat treatment around 1,100 ° C., and the falling coke powder coke is generated in the process of transferring the manufactured coke to the furnace. Therefore, the physicochemical characteristics of these two powdered cokes are judged to be similar.

CDQ powder coke is produced by cooling 21.6 tons of coke near 1,100 ℃ to 180 ℃ over 3-4 hours by using nitrogen gas, and the physical properties are different from those of the above two powdered cokes. Judging.

In order to select materials for adsorption from such powdered coke (or powdered coke), the following tests should be carried out. At this time, powder coke of the same particle size should be selected and the surface area should be measured by the surface area analyzer.

After preparing 70-170mesh powder coke, BET surface area for nitrogen was obtained, and the results as shown in Table 1 below were obtained.

From the results of Table 1, the BET surface area of powder coke was 0.68 m < 3 > / g, digester powder coke 1.21 m < 3 >

From Gibbs isotherm, the relationship between the adsorption surface area and the partial pressure of adsorbate is shown in equation (I).

[Formula 1]

In Equation (1), p is the partial pressure of the adsorbate, A is the surface area of the adsorbent, and β is the area or volume of the adsorbate molecule. B2A in formula (I) = 2β / A

[Formula 2]

In equation (2), b is the Langmuir equilibrium constant. On the other hand, if you change the expression ((2) to Langmuir type, it becomes as (3)

[Formula 3]

In formula (3), q and qs are adsorption amount and saturated adsorption amount in adsorption partial pressure p, respectively.

So in the above equations, if the same kind of adsorbate is adsorbed at the same concentration or at the same partial pressure, It can be seen that the larger qs also becomes larger. In other words, this indicates that the larger the surface area, the larger the amount of adsorption in general.

Therefore, it is most preferable to use the CDQ powder coke having the largest specific surface area as the adsorbent.

Next, the appropriate particle size range of the selected powder coke should be selected.

In order to understand the particle size distribution of each powder coke, it is classified into 5, 10, 20, 35, 50, 70, 100, 170 mesh standard mesh, and the weight of coke in each standard mesh is measured to determine the ratio of the total coke. The obtained results were obtained as shown in Table 2 below.

In Table 2, the particle size of the light fall powder coke was 41.9% for the whole, 53.5 to 43.5% for the whole, 43.5% for the 50 to 170 mesh, 8.6% for the mesh and 5.3% for the smaller than 170mesh. The digester powder coke was 19.7% for 5mesh and 2.9% for smaller than 170mesh. CDQ powder coke was found to be 0.005% larger than 5mesh, 23.42% of 5-50mesh, 45.4% of 50 ~ 170mesh, and 30.6% of smaller than 170mesh.

That is, the size of the particle size was found to be CDK powder coke of the falling down digestion, in particular, the falling light is more than 5mesh, CDQ is more than 170mesh.

Therefore, except for powders of 170 mesh or less that are too fine and difficult to handle in the particle size distribution of CDQ powder coke selected as a suitable material for use in the present invention, powders of 50 mesh or more that are too coarse and difficult to use as fluidized bed adsorbents in wastewater treatment are used. It is preferable to prepare the adsorbent of the present invention by selecting a powder having a particle size distribution in the range of 50-170mesh.

Among the particle size distributions of the CDQ powder coke, powder having a particle size distribution in the range of 50-170mesh occupies about 67%, so that most of the CDQ powder coke can be utilized.

The powder coke contains a significant amount of ash. Table 3 below shows the chemical composition of powder coke.

In Table 3, about 11.28% of inorganic matters (ash) were contained, and when eluted with hydrofluoric acid, pores were developed at the site where minerals disappeared, so that the surface area increased, and it was found from the above formulas (1) to (3). As can be seen, the adsorption capacity is also increased.

The concentration of hydrofluoric acid used in the acid treatment is preferably about 15-30%, since the improvement of adsorption capacity is not noticeable at concentrations of 15% or less, and the increase in concentration does not occur any further at concentrations above 30%. to be.

In addition, waste hydrofluoric acid generated during the acid treatment was recycled during hydrofluoric acid treatment by adjusting the concentration of hydrofluoric acid, condensing the hydrofluoric acid, and reinjecting the hydrofluoric acid to 15-30%.

EXAMPLE

CDQ powder coke was selected using only a standard having a particle size distribution of 50-170mesh, and put into various concentrations of hydrofluoric acid and hydrochloric acid solution and reacted with stirring for about 48 hours. Water was washed several times and coined, put in a 105 ℃ oven and stored in a desiccator.

A certain amount of the adsorbent stored in the desiccator was added to 250 ml of waste water having 80 ppm of COD, and stirred for about 48 hours. The residual COD was measured to calculate the adsorption capacity of the acid treated powder coke.

The results are shown in FIGS. 3 and 4.

From the results of FIG. 3, hydrochloric acid showed little improvement in adsorption capacity at the concentration of 4.8%, whereas hydrofluoric acid was significantly improved in hydrofluoric acid. In addition, even at the concentration of 9.6%, the adsorption capacity was remarkably improved in the case of hydrofluoric acid compared to the degree of improvement in the adsorption capacity of hydrochloric acid.

Moreover, although the improvement degree of the adsorption capacity according to the concentration of hydrofluoric acid is shown in FIG. 4, it can be seen from the graph that an appropriate concentration of hydrofluoric acid is 15-30%.

The adsorbent produced by the method of the present invention is simple in manufacturing method and the material is inexpensive. That is, a large amount of powdered coke is generated as a by-product from the iron and steel coke plant, and is currently used mostly for fuel, and the price is about 1 / 30-1 / 100 of activated carbon.

In addition, waste hydrofluoric acid is economical because it can be recycled.

Conventionally, coke has already undergone heat treatment at about 1100 ° C., and crystallization is considerably progressed, and it is known that there is almost no adsorption force. Despite the above-mentioned advantages, almost no attempt has been made to use it as an adsorbent. The adsorbent which was excellent in the performance of powder coke could be manufactured by the method of selecting and performing pretreatment on suitable conditions.

Claims (2)

In the method for preparing adsorbent using powder coke, the powder coke generated in the CDQ process is selected to have a particle size of 50-170mesh, and then treated with hydrofluoric acid at a concentration of 15-30%, followed by sufficiently washing with water and drying. Adsorbent production method using a CDQ powder coke, characterized in that configured. The method of claim 1, wherein the waste hydrofluoric acid generated during the hydrofluoric acid treatment is recovered by distillation, condensation, and recycled by adjusting to a concentration of 15-30%.