Abstract
In continuation of the present authors’ studies on production of high strength coke from lignite by sequential binderless hot briquetting and carbonization, this study has been carried out aiming at proposing methods to produce high strength coke from non-/slightly caking coals of subbituminous to bituminous rank. This paper firstly demonstrates preparation of cokes with cold tensile strengths above 10 MPa from two single non-caking coals (particle size; < 106 µm) by applying briquetting at temperature and mechanical pressure of over 200°C and 100 MPa, respectively. Such strength of coke is obtained over a wide range of heating rate, 3–30°C/min, during carbonization with final temperature of 1000°C. Then, a simple pretreatment, fine pulverization of coal to particle sizes smaller than 10 or 5 µm, is examined. This pretreatment enables to prepare coke with tensile strength even over 25 MPa, by decreasing porosity of resulting coke and more extensively the size of macropores simultaneously. The coke strength changes with carbonization temperature having a particular feature; significant development of strength at 600–1000°C, i.e., after completion of tar evolution, in which macropores and non-porous (dense) part of coke shrink in volume, inducing bonding and coalescence of particles and thereby arising the strength.
1. Introduction
Technologies for producing coke available in blast furnace operation from non- and slightly caking coals, in other words, without caking coals, are desired for sustainable ironmaking.1) Studies on binderless coal briquetting at ambient temperature,2,3,4,5) 300–350°C6) or 300–500°C7) were reported previously. Following those studies, the present authors8,9,10,11) proposed binderless briquetting of lignite at temperature up to 200°C by taking advantage of its thermophysical behavior; a sort of plasticization that is arisen from local mobility of relatively flexible macromolecular network.12,13,14) The hot briquetting enabled to prepare highly densified briquettes from a Victorian lignite.8) Subsequent carbonization by heating the briquettes up to 900°C transformed them into cokes with tensile strength ranging from 20 to 40 MPa.8) Such strength was much greater than that favored for use in blast furnace, around 5 MPa.15,16,17,18) This work was followed by those on coke preparation from hydrothermally treated Indonesian lignites,9) coke preparation from Victorian lignites pretreated by acid washing and others,10) and lignite properties and briquette thermal behaviors influencing coke strength.11) In terms of conventional properties relevant to coke production by coke-oven method, such as Gieseler maximum fluidity and surface reflectance, lignite is a worst type of feedstock.19) Thus, the above-mentioned studies showed possibility of producing high strength coke only from non-caking coal/lignite (i.e., those having no or little fluidity upon heating) even without binder.
Direct application of lignite-derived coke, however, encounters problems ranging from safe transportation of lignite to use of coke with stable operation of blast furnace. A most serious problem associated with a typical lignite property is extraordinarily high reactivity with CO2. This is arisen from abundance of inherent organically-bond metallic species such as Na, Ca and Fe that have catalysis in coke reaction with CO2.20,21) Acid washing of lignite prior to briquetting is a most effective way to remove such catalyst precursors from a chemical point of view. In fact, the reactivity of coke from a type of acid-washed Victorian lignite had sufficiently high strength and low reactivity (as low as that of coke from a typical strongly caking bituminous coal).10) It is, however, difficult to introduce a wet and such a chemical process in coke making process. In-situ catalyst deactivation by promoting reactions between the catalyst precursor and acidic mineral matter was proposed. The overall catalytic activity of coke from a Victorian lignite was in fact lowered by about 3/4 by blending silica with the lignite prior to briquetting. But, such a degree was not necessarily enough.22)
In view of the above, the present authors propose to apply the above-described sequence of binderless hot briquetting and carbonization to production of high strength coke from non- and slightly-caking subbituminous or bituminous coals. Firstly, it is expected that reactivity of cokes from those coals is higher than but similar to that of current commercially available cokes. Secondly, non-/slightly caking coals are already used for coke production as components of coal blends with well-established supply chains over the world. On the other hand, it is believed that organic matrices of subbituminous/bituminous coals are less plasticizable than lignites at temperature as low as 100–200°C.12,13) It may therefore be necessary to introduce a reasonable and effective pretreatment before the briquetting.
This paper firstly reports successful preparation of high strength cokes from a non-caking subbituminous coal and another bituminous coal through optimization of operating variable for briquetting and carbonization. Secondly, important finding of effectiveness of a pretreatment, that is, fine pulverization, is shown together with its essential roles in occurrence and development of coke strength. Finally, mechanism of occurrence of coke strength that is particular to briquette-derived coke, is discussed based on behavior of coke during the carbonization.
2. Experimental
2.1. Coal Samples
A bituminous coal (WH) and a sub-bituminous coal (KP) were employed as the main starting coal samples. Each coal was pulverized to sizes smaller than 106 μm, dried at 40°C under vacuum until the moisture content decreased to ca. 10 wt% on a wet basis, and then stored until use. Table 1 shows properties of the coal samples after the above preparation. The maximum Gieseler fluidity of WH and KP were both around 0 in the log(ddpm) unit. For investigating the effect of blending of WH with a caking coal, a bituminous coal was used. The composition of this caking coal was as follows: C: 80, H: 4.3, N: 1.9, Ash: 9.4 wt%-dry). The caking coal was pulverized to sizes smaller than 106 μm before the blending.
Table 1. Properties of WH and KP coals.
| Coal | WH | KP |
|---|
| Elemental composition, wt% on dry basis |
| C | 74.1 | 69.0 |
| H | 4.8 | 5.1 |
| N | 1.7 | 1.5 |
| O+S (by diff.) | 12.7 | 17.7 |
| ash | 6.7 | 6.7 |
| Particle size distribution, wt% for each fraction |
| 106–75 μm | 41 | 16 |
| 75–53 μm | 29 | 19 |
| 53–38 μm | 25 | 21 |
| < 38 μm | 5 | 44 |
WH and KP were subjected to some different pretreatments, details of which are reported below.
2.2.1. Ball Milling for Fine Pulverization
The coal sample with a mass of 10 g-dry was charged in a polypropylene-made bottle (volume; 0.25 L) together with zirconia-made balls (diameters; 10 mm, number; 166). The bottle was rotated at 150 rpm on a pot mill (Nitto Kagaku Co., Ltd., model ANZ-61S) for 10, 20 or 30 h. KP was also pulverized gently and carefully for collecting two fractions with particle size ranges of 106–250-μm and 250–500-μm.
2.2.2. Chemical Demineralization
The sample (5 g-dry) was dispersed in an aqueous solution of HCl (conc.; 3.0 mol/L, volume; 0.15 L, temp.; 60°C) under continuous stirring for 20 h. The solid was separated from the solution by filtration, and washed with deionized water repeatedly until no chlorine ion was detected in the washing. Then the solid was treated in another aqueous solution of HF (conc.; 3.0 mol/L, volume; 0.15 L, temp.; 25°C) in the same way as above, and dried at 60°C under vacuum until the moisture content decreased to ca. 10 wt%-wet. The ash contents of the acid-washed WH and KP were 0.0 and 0.1 wt%-dry, respectively.
2.2.3. Blending of WH with Caking Coal
WH was mixed with caking coal manually in a ceramic mortar (for avoiding further pulverization) at a mass ratio of 90:10 or 50:50.
2.2.4. p-Cresol Sorption
WH was also subjected to another type of physical pretreatment. The coal (5.0 g) was changed in a SUS316-made tubing bomb together with p-cresol (reagent grade, 0.5 or 2.0 g) and N2 (purity; > 99.9999 vol%) at a pressure of 1 MPa. After closed, the bomb was heated at 240°C for 2 h, and cooled to ambient temperature. p-Cresol was employed with an expectation that it played a role of plasticizing the organic matrix of WH. It is known that p-cresol as well as other phenolic compounds are major components of light fraction of tar from coal pyrolysis, and those are easily adsorbed/absorbed into coal matrix from vapor phase.23)
2.2.5. Binderless Briquetting
Every coal sample was transformed into briquettes in the same way as that reported by the present authors.8,9,11) The conditions are as follows: coal mass; 1.0 g-dry, dimension of mold; 15 mm in diameter and depth in 20 mm, briquetting temperature (Tb); 100–240°C, briquetting pressure (Pb); 32–128 MPa, period of mechanical pressure loading; 8.0 min, typical dimension of briquette in form of disc; ca. 14 mm and 5 mm in diameter and thickness, respectively.
2.2.6. Carbonization for Preparation of Coke
The briquette was heated in atmospheric flow of N2 (purity; > 99.9999 vol%, flow rate; 200 ml-stp/min) at a heating rate (α; 3, 10, 20 or 30°C/min) to a final temperature (Tc; 400, 500, 600, 700, 800, 900 or 1000°C) with a 10 min holding time at Tc.
2.2.7. Coke Strength Measurement
4–8 coke samples prepared under the same conditions for pretreatment, briquetting and carbonization were subjected to mechanical strength testing, and their tensile strengths were measured in an indirect way. Details of the measurement was reported previously.8) For all the sets of coke samples, deviation of the measured tensile strength (σ) was within ±10% from the average.
2.2.8. Other Analyses
Scanning electron microscopy was applied to qualitative evaluation of porous nature of coke by observing fractured surfaces before or after polishing. Mercury porosimetry was employed for quantitative analysis of macropores (pore size range; 0.01 to 10 μm). Total volume of micropores (size < 2 nm), mesopores (2–10 nm) and macropores (10–10000 nm) was measured by gas pycnometry with helium (purity; > 99.9995 vol%).
3. Results and Discussion
3.1. Effects of Operating Variables for Briquetting and Carbonization on Coke Properties
The combined effects of operating variables for the briquetting and carbonization on the coke strength were investigated systematically for WH without pretreatment. Figure 1 shows results. σ increases with Pb, Tb and also Tc, as expected from the authors’ previous studies.8,9,11) The strong positive effects of Tb and Pb on σ indicate that the organic matrix of WH, heated at 100°C or higher temperature, is ready to be plasticized to a more or less degree under mechanical pressure, although the temperature of 100–240°C is much lower than plasticizing or softening temperature without pressure defined by a needle penetrometry, 320–380°C for bituminous coals.24,25) Such plasticization is supported by the data shown in Fig. 2. The bulk density of briquette, ρb, increases with Tb as well as Pb. Such ρb increase is a result from more extensive deformation of WH particles and decrease in the voidage in briquette and probably also void size.
As seen in Fig. 1(c), the effect of α on σ is, if any, very limited over the entire range examined. The applicability of α as high as 30°C/min is important, because a higher heating rate directly leads to a shorter time for the carbonization and also compact coker. It is believed that a non- or slightly caking property of coal is even advantageous in rapid carbonization, in which swelling due to fluidity occurrence should be inhibited. Figure 1(d) shows that the coke strength occurs at temperature over 500°C or higher, in other words, after completion or near completion of tar evolution, in other words, after re-solidification.24,25) The mechanism of strength occurrence and development are discussed in more detail later.
Importance of the briquetting conditions, i.e., Pb and Tb, is discussed. Figure 3 shows relationships between ρb of WH briquette and density of resulting coke (ρc). It is, in overall, clear that higher ρb results in higher ρc. There is a single relationship between ρc–ρb for the WH cokes after carbonization with α = 30°C/min. It is also seen that the ρc–ρb depends on α. A higher density, probably due to a lower porosity, of formed coke normally leads to higher tensile strength of coke.8,9,11) However, such a trend does not necessarily apply to cokes prepared by employing different α. As already shown in Fig. 1(c), α is not influential on σ. Namely, cokes from carbonization at higher α have lower ρc, while having σ equivalent to that for lower α. Although not examined in detail, it is estimated that higher α causes slight plasticization or softening of WH (but more extensively than lower α), promoting particles bonding, enhancing pore formation and/or development. This estimation is supported by a negative effect of α on the coke yield (see Supporting Information I), which is an indication of enhanced depolymerization and tar evolution with greater α.
The relationship between σ and ρc is more complex than the ρc–ρb relationship, as shown in Fig. 4. σ of coke is influenced combinedly by α, Pb and Tb. If a coke with greater σ and lower ρc is preferred in its application to blast furnace ironmaking, applying higher α is a better choice. Applying higher α together with lower Pb (but with Tb as high as 240°C) is also reasonable, if the coke has sufficiently high σ. It is noticed from the comparison between the plots A and B that applying Pb as high as 128 MPa is not so effective for ρc unless Tb is as high as 240°C. This is probably due to that applying higher Pb at lower Tb, in other words, applying unreasonably high mechanical pressure to ‘less plasticizable’ WH, causes residual stress inside the briquette, or otherwise, due to that densification by applying higher Pb does not necessarily lead to either adhesion or bonding of WH particles. Comparison of the plots B with C indicates that lower α is effective for increase in ρc but not necessarily for that in σ. The effect of α on σ was investigated in more detail by adding the conditions with α = 10 and 20°C/min. As shown in Fig. 5, higher α results in higher ρc, but without increasing σ. Thus, α appears to have little or no effect on σ, but this does not mean essentially no effect. Then, the α effect on the coke property, together with effects of the other variables, was examined by physical coke structure.
Figure 6 displays SEM photographs of polished surfaces of WH cokes prepared with different combinations of Pb, Tb, α or Tc. Comparing the photograph (c) with (b) reveals that increasing α from 3 to 30°C/min causes formation of greater domains (detected as flat top surfaces after polishing), and this suggests enhanced plasticization (or softening) of WH upon heating in a certain temperature interval. It is also seen that such greater domains do not occur if Tb is as low as 100°C (compare (a) with (b)). Photograph (d) from coke (exactly saying, semi-coke from carbonization with Tc = 500°) should be noted because this micrograph evidences formation of greater domains during heating at 500–1000°C probably due to particles’ bonding and coalescence ‘after completion of the tar evolution and so-called re-solidification’. This is consistent with considerable increase in σ at 500–1000°C. Taken together with the results shown in Figs. 1, 2, 3, 4, 5, that in Fig. 6 demonstrates that the variables Pb, Tb, and α are all important for the strength of WH coke, but exactly saying, these are important for letting the briquette be ready for the strength occurrence in the carbonization at temperature of 500–1000°C. The mechanism of the coke strength occurrence and development are discussed in more detail in Section 3.3.
This section reports effects of the pretreatments on σ of cokes from WH and KP. Figure 7 summarizes results for the cokes from pretreated WH’s. The p-cresol sorption at 10 wt% increases σ from 10.7 to 13.7 MPa, and this is explained by the role of p-cresol as plasticizer that enhances particles’ deformation and adhesion in the briquetting. However, overloading of p-cresol is not effective because it causes eruptive vaporization of p-cresol forming cracks within the briquette. The blending of the caking coal with WH increases σ to 14.4 and 17.0 MPa at ratios of 10 and 50 wt%. It is thus demonstrated that blending caking coal, if its mass fraction is in a proper range, is effective and reasonable way to increase the coke strength. Though not shown, the briquettes made exclusively of the caking coal were prepared and carbonized. The resulting coke had σ as small as 2–3 MPa. This was, without saying, due to irreversible and pronounced swelling of the briquette at 400–500°C.
The most important result among those shown in Fig. 7 is σ as high as 27 MPa of the coke from ball-milled (finely-pulverized) WH. It was initially suspected that the fine pulverization of mineral matter had reduced or eliminated stress concentration points arisen from mineral grains. This suspicion was, however, not reasonable. The demineralization gives a positive influence on σ, but it is much less than the fine pulverization of both the organic matrix and mineral grains.
The fine pulverization was further investigated by employing KP, which was subjected to the ball milling for 10, 20 and 30 h. KP samples with particle sizes of 106–250 and 250–500 μm were used for the briquetting. Figure 8 shows SEM photographs of KP particles before and after ball milling. Measurements of the particle size distributions by methods such as light scattering spectroscopy were considered but not performed because of difficulty in eliminating ‘agglomeration’ even in an appropriate liquid (dispersant). It was confirmed by semi-quantitative analysis of SEM photographs that the fine pulverization for 10 h and 20–30 h decreased the size of KP particles to < 10 µm, and < 5 μm, respectively. Though not shown, coke samples were also prepared from the demineralized KP. σ for the coke from this demineralized coal was 13.6 MPa. It was believed that the elimination of not only the mineral matter but also organically-bound metallic species induced such increase in σ. It is known for the pyrolysis of lignites and subbituminous coals that the elimination of such metallic species promotes depolymerization of macromolecular network allowing formation of more tar precursor (as plasticizer) and then evolution of more tar.26,27) However, the positive effect of demineralization on σ was smaller than that of the fine pulverization.
Figure 9 presents the effect of particle size of KP on σ of resulting coke. The fine pulverization increases σ from 10.2 to 22–27 MPa depending on the ball milling time. It is also seen that KP with greater particle sizes gives smaller σ. It is thus concluded simply and clearly that the enhanced coke strength is arisen from decreased or much decreased particle sizes of the feedstock coal. Figure 10 visually shows the particle size effect on a coke property, pore size. It is clear that the fine pulverization remarkably reduces the size of pores in the coke.
The particle size of KP greatly influences other properties of briquette and coke. As seen in the top graph of Fig. 11, ρb increases by decreasing the particle size, while the decrease is within a relatively narrow range from 1.12 to 1.22 g/cm3. On the other hand, ρc ranges over 0.67–1.30 g/cm3. When KP with dp = 250–500 μm or that with dp = 106–250 μm is briquetted and then carbonized, the density decreases during the carbonization substantially. On the other hand, when dp < 106 μm, the bulk density is maintained or even increased during the carbonization. It is therefore estimated that the briquette of KP with greater particle size undergoes breakage of the original densified structure upon heating, losing its initial high density. The particle size also influences the chemical behavior of the briquette in the carbonization. As seen in the bottom graph, the coke yield increases with ρc from 57 to 63 wt%-dry-briquette. It is believed that the diffusion of the tar precursor is suppressed to a substantial degree within the pyrolyzing briquette of the finely pulverized KP.
Figures 9, 10, 11 show that the fine pulverization, more generally, the decreasing particle size increases the briquette and coke densities, decreases the pore size, and then greatly increases σ. This section reports the effect of the particle sizes of WH and KP on the porous properties of the corresponding cokes quantitatively, making a focus on macropores that are detectable by the mercury porosimetry. Figure 12 shows the effects of Tb, Pb and particle size on the pore size distribution for WH coke. Comparison of Graph (a) with (b) and that of (a) with (c) demonstrate that increasing Tb and Pb both reduce the porosity of resulting coke while shifting the pore size distribution toward smaller size to more or less extents. A noticeable particle size effect on the pore size distribution is seen in Graph (d). A major portion of the pore volume for the coke from the finely pulverized WH, more than 90%, is attributed to pores with sizes smaller than 1 μm. On the other hand, without the fine pulverization, the volume fraction of the pores smaller than 1 μm is only 36%. Graph (d) also shows that the fine pulverization is effective on decrease in the macropore volume. As shown in Fig. 13, the fine pulverization of KP causes decrease in the micropore volume and pore size of resulting coke in the same manner as for WH.
Graphs (a)–(e) of Fig. 14 plot properties of the cokes from KP and a finely pulverized KP (ball milling time; 10 h) against Tc. In the briquetting and carbonization of those coals, Tb = 240°C, Pb = 64 MPa and α = 10°C/min were applied. σ of the coke from the finely pulverized KP is always much greater than that from KP with particle sizes of < 106 μm (Graph (a)), and this trend seems to be consistent with higher ρc as well as smaller total porosity (Graphs (c) and (d)). On the other hand, as seen in Graph (b), the fine pulverization has no or very little effect on the true density that is determined the chemical carbon structure. Thus, consistent with the results presented in Figs. 11 and 13, Fig. 14 demonstrates that the greatly positive effect of the fine pulverization on σ is attributed mainly to decrease in the porosity and pore size of coke.
The mechanism of occurrence of the coke strength is here discussed based on the results shown in Fig. 14. For both KP and the finely pulverized KP, σ increases significantly at 600–1000°C. This trend is interpreted as the development of coke strength after completion of the tar evolution, in other words, after so-called re-solidification. Plasticization or softening may be an important event for particles’ bonding and coalescence, but this cannot be concluded because there is insignificant increase in σ at temperature of 400–600°C where ρc even decreases slightly. Graph (e) of Fig. 14 shows monotonous decrease with Tc of the volume of the dense (non-porous) part of briquette (or coke), in other words, its shrinkage. Graph (f) shows relationships between the relative non-porous part volume and relative mass of coke. There are two different modes of the volume shrinkage at 400–600°C and 600–1000°C. At the former range of Tc, the net shrinkage in bulk occurs mainly due to release of volatiles (i.e., mass release) by the pyrolysis, but in the latter range due to shrinkage of the non-porous part (i.e., its densification) rather than the mass release. Though not shown here, it was found that the net macropore volume decreased at a rate similar to that of the non-porous part. The results from the mercury porosimetry of KP cokes with Tc = 600 and 1000°C are available in Supporting Information II. It was also found that the porosity increased with Tc, as seen in Graph (d), which was caused by net increase in the volume of micro-/meso-pores, which is shown later.
Figure 15 shows net changes in the volumes of micro-/meso-pores (VP-micro/meso), macropores (VP-macro) and non-porous part (VNP) of coke from KP and finely pulverized KP in the course of raising Tc from 600 to 1000°C. All the volumes are indicated as those per gram of briquette. VP-micro/meso was calculated based on the following equation
Total volume of coke = VP-micro/meso + VP-macro + VNP.
VNP greatly decreases due to its own densification rather than mass release. On the other hand, the total pore volume changes only slightly, and this is a result from increase in VP-micro/meso and decrease in VP-macro.
In consideration of the strength of coke, its volume can reasonably be classified into two parts; that of macropores and the others (i.e., those of non-porous part and micro-/mesopores). This is because stress concentration is believed to occur at macropores exclusively. Table 2 shows the changes in VP-macro and (VP-micro/meso + VNP) in Tc intervals of 600–1000°C. For both KP and ball-milled KP, the net decreases in the macropore volume is 25 to 27% and similar to that of the other part. Thus, the coke shrinks in bulk volume being contributed by shrinkages of the macropores and the others at similar degrees.
Table 2. Changes in
VP-macro and (
VP-micro/meso +
VNP) during carbonization at 600–1000°C.
| Feedstock | VP-macro [cm3/g-briquette] | VP-micro/meso + VNP [cm3/g-briquette] |
|---|
| Tc = 600°C | Tc = 1000°C | Reduction rate | Tc = 600°C | Tc = 1000°C | Reduction rate |
|---|
| KP | 0.15 | 0.11 | 25% | 0.53 | 0.40 | 24% |
| 10 h-Ball-milled KP | 0.13 | 0.095 | 27% | 0.52 | 0.40 | 23% |
It is believed that the occurrence of coke strength is driven by the above-described shrinkage of coke. As shown in the SEM photographs, (c) and (d) of Fig. 6, the volumetric shrinkage caused bonding and coalescence of particles even after the period of pyrolysis-induced plasticization or softening at Tc < 600°C. The present authors recently studied coke preparation from twelve types of lignites through hot briquetting at 200°C applying mechanical pressure of 25–112 MPa and carbonization with final temperatures of 1000°C.11) It was claimed that the tensile strength of coke, which ranged up to 31 MPa, was correlated well with the shrinkage of briquette in bulk volume. The authors also found that the strength of coke from hot-briquetted Victorian lignite (Loy Yang) remained almost unchanged at 400–600°C, but increased remarkably at 600 to 1000°C. (unpublished results. see Supporting Information III). Taken together with the above-mentioned previous results, it is concluded that the coke strength occurs through bonding/coalescence of non-, weakly-bonded, and/or just-in-contact particles at temperature above 600°C, which is driven by the volumetric shrinkages of macropores, micro-/mesopores and non-porous part.
4. Conclusions
The present authors studied coke preparation by carbonization of briquette of pulverized non-caking WH and KP coals, and have drawn the following conclusions.
(1) Sequential briquetting of pulverized coal (particle size; < 106 μm) at Pb = 128 MPa and Tb = 240°C and carbonization with Tc = 1000°C and α = 3–30°C/min produces coke with σ > 10 MPa.
(2) The fine pulverization of coal to particle sizes of < 5 μm enables to production of coke with σ > 25 MPa.
(3) The fine pulverization causes both porosity and pore size of resulting coke decrease, thereby increasing σ significantly.
(4) Coke strength over 10 MPa occurs during carbonization at 600–1000°C, where macropores and non-porous (dense) part shrink in volume by around 25%, driving bonding and coalescence semi-carbonized particles.
Acknowledgment
A part of this work was financially supported by The Iron and Steel Institute of Japan for 2015–2018. The authors are grateful to Cooperative Research Program of Network Joint Research Center for Materials and Devices that has been supported by the Ministry of Education, Culture, Sports, Science and Technology, Japan. Technical support by Mr. Takahiro Ohsako, who was a student of Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, is acknowledged. An author of this paper, Cheolyong Choi acknowledges the Kyushu University Program for Leading Graduate Schools: Global Strategy for Green Asia for his financial support.
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