Charcoal Production Trial MPDF GRET Report 1 120607-2

8/14/2019 Charcoal Production Trial MPDF GRET Report 1 120607-2

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GRET LDP project Bui Ngoc Long Patrice Lamballe

Production trial of bamboo luong charcoal

and activated carbonAssignments in need of implementation and completion

GRET and LDP project participate in the provision of technical assistance to workshops,

including main assignments as follows:

1) Carrying out first production trial.

2) Adjusting techniques- technology of building and burning kilns

3) Reviewing financial and technical aspects of production

4) Making proposals on future investment in charcoal production sector

1. Preparation work

a. Transferring primary production equipments to existing workshops

It is concluded after discussion with workshop owners and based on the workshops

needs and demand as well as their strategy, financial situation and land availability.

o Three workshop owners expressed their concern and agreed to the establishment

of kilns (X1, X2 and X4); X3 has no interest in coordination with X5

o X2 is not suitable for charcoal production because the workshop location lies in anarrow area, failing to provide enough space for building a kiln.

o To make up for this, all workshops allow using X5 as the third trial. Therefore,

charcoal production is carried out in 3 workshops: X1 (Thien Phu - Quan Hoa),

X4 (Dien Chung Ba Thuoc) v X5 (Xuan Phu Quan Hoa)

b. Preparing construction materials

o Materials collected on-site (cement, sand, bricks): Bricks, sand are materials

produced and available in the region. Cement is also available near the

construction site, its price is nearly similar to that is in the plains market (only

higher by 7-10%).

o Materials purchased from Thanh Hoa: (glass wool, refractory bricks, glass liquid):

these are special materials used for refractory structure of the kiln. They are not

available in the region (including Thanh Hoa city) and have to be ordered from

companies of refractory materials in Bac Ninh, Thai Nguyen at very high price:


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Refractory brick: Price offered by the Factory is 1,700 VND/Kg, equivalent to

6,000 VND/unit (each brick unit weighs 3.5 Kg on average) excluding

delivery fees.

Glass wool: 18,000 VND/kg.

- After studying the market, the team bought refractory bricks and glasswool from Thanh Hoa ceramic company at the price equivalent to 60% of

market price (3,500 VND/brick unit, 1,000 VND/Kg glass wool)

- However, there is not high amount of these materials left. Therefore, on

building the new kiln, material cost should be calculated according to

factorys price.

c. Collecting raw materials

o After finishing the kiln, it takes at least 1-2 days to dry it before loading material

for burning trial. The first burning time aims to dry the kiln and check itstechniques so it is not necessary to take consideration of material and product

quality.

o From the second one, it is necessary to monitor burning techniques to identify

product quality. Different kinds of material have different period of burning :

For dry and thin material: burning time is short (ex. X4;1, its to say, the first

cycle of kiln build in X4 workshop)

For thick and fresh material: burning time is prolonged (ex. X4;3)

o To make products with good quality:

Materials for burning should be fresh poles,

Aged 3 years old or more and

Not spongy

Then after burning, the whole kiln will be evenly dried, with high temperature and

high quality products.

o Poles with thick wall and small perimeter will take time for fire distribution,

requiring long time of burning and cooling which leads to maximum temperature

inside the kiln and makes products with high quality and suitable for activated

carbon production.

d. Supporting kiln building


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After studying reference documents of INBAR on techniques of building kiln and

technology of burning carbon with anaerobic kiln, GRET research team assigned two

officers to carry out following works:

o Studying techniques of loading and burning carbon in anaerobic conditions

according to the traditional method used by some villages and workers of burning

carbon in Tan Thanh, Luan Thanh communes of Thuong Xuan district, Hop Tien,

Hop Ly communes in Trieu Son district, and mountainous areas in Thanh Hoa

province.

o Carrying out burning trial of 3 rudimentary kilns in Kien Tho commune, Ngoc

Lac district - Thanh Hoa for testing burning technology and learning experience.

o Visiting workshops of charcoal production from bamboo luong in provinces of

Hoa Binh (Mai Chau and Ky Son districts), Vinh Phuc, to select building

technology and the kiln shape as well as study more about information of

techniques, market and price of each product.

o Referring to teachers of Hanoi university of technology and some workshops of

ceramic production in Thanh Hoa on techniques and technology of building

refractory kiln, and finally:

- Calculating and designing kiln model - estimating material cost - making

estimates of cost and plan of building kiln for workshops.

1. Burning gate - 2. Place of loading firewood - 3. The frontwall 4. Smoke of luong material 5. Way of burning

temperature 6. The kiln dome made of brick - 7. The backwall 8. Chimney

Fig. 12: Diagram of the burning kiln made of brick

1

2

567

1

8

4


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- Expenses related to kiln building:

TT Details

Kiln X4

( Simple kiln)

Kiln X1

(Double kiln)

Kiln X5

(Big double kiln) Total

I Materials 16,150,000.00 28,030,000.00 35,650,000.00 80,155,000.00

1

Refractory

brick 7,000,000.00

12,250,000.

00 14,000,000.00 33,250,000.00

Glass liquid 500,000.00 500,000.00 750,000.00 1,500,000.00

2

Asbestos

fiber 2,000,000.00

3,000,000.

00 4,000,000.00 9,000,000.00

33mm ironsheet 2,500,000.00

4,500,000.00 6,250,000.00 13,250,000.00

4 Normal brick 1,800,000.00 3,500,000.00 4,000,000.00 9,525,000.00

5 Cement 750,000.00

1,500,000.

00 2,250,000.00 4,750,000.00

6 Sand 200,000.00

640,000.

00 400,000.00 1,440,000.00

7 Slag, scoria 500,000.00

640,000.

00 1,000,000.00 2,040,000.00

8 Delivery 900,000.00

1,500,000.

00 3,000,000.00 5,400,000.00

II Labour 4,100,000.00

5,370,000.

00 5,250,000.00 14,720,000.00

Total 20,250,000.00 33,400,000.00 40, 40,900,000 94,875,000.00

* Refractory brick, glass liquid and glass wool are structural material composition

located deep inside aiming at ensuring maximum burning temperature of the kiln and

products with highest quality (activated carbon) due to the following effects:

- Completely preventing the inside heat from releasing

- Absorbing and storing heat inside the kiln to reach maximum

temperature degree.

- Assisting the kiln to have high refractoriness and resistance against

cracks on the wall inside the kiln.- The rest material is the kiln frame

o During burning, there should be two project staff taking turns to be present at the

workshop, to provide instruction on techniques of anaerobic burning to the

building workers.


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o Workshops have searched and mobilized skilled brick-layers on-site to carry out

construction:

Each workshop hires 1 group of workers to carry out construction; these groups

have different capability, leading to delivering kilns with different quality.

On the other hand, due to research activities for learning experience performed

after each kiln building, the one which was built later has better quality and

lower construction fees than the previous one:

Kiln X4:

- After exchanging and reaching agreement with workshops, the research

team and X4 made first construction plan of only a simple kiln. After

finishing the kiln, they had trial burning performed for a period. X1 was

only built after exchanging and drawing experience of X4 first kiln.

Kiln X1:

- X1 was built as a double kiln, with thicker composition to ensure its

tightness and firmness. The cost to build this kiln is equivalent to 80% of

X4 cost (for each kiln).

Kiln X5:

- After firing X1 for two periods, the research team together with

workshops reviewed coal quality, discussed the kiln structure, firing

technology and recognized that more studies need to be done on

technology of building kiln and burning coal in Lam Dong province,

before building a kiln in X5.

- After studying more about techniques of building kiln in Lam Dong and

from advices of the experts visiting the workshop, it is necessary to

change its design (building the kiln in round or ellipse shape) to ensure

higher temperature inside the kiln. However, this shape of kiln can lead to

difficulty in techniques of building the cover, technology that requiresskilled workers with much experience in doming and having enough care

in their work.


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2. Carrying out first production periods and checking coal quality

a. Building and performing burning trials in X4 kiln :

1. From 20/1 to1/2 building simple kiln in X4 (Dien Trung commune)

- Size of the kiln:

+ Inside: 2.7 x 1.5 x 1.5 m

+ Outside: 4 x 2.8 x 2.0 m.

- Structure:

+ The first layer: 24 cm fire-resistant brick

+ The second layer: glass wool of 5 cm thickness

+ The third layer: kiln residues (slag) of15 cm in thickness.

+ The forth layer: normal brick for kiln wall of 21 cm in thickness.

+ Parabolic-shaped dome in 4 layers with domed frame made of iron.

o Expense details of building X4:

No. Details Unit Amount Unit price Total

I Materials

1 Refractory brick Brick unit 2000 3,500.00 7,000,000.00

Glass liquid Kg 200 2,500.00 500,000.002 Asbestos fiber kg 200 10,000.00 2,000,000.00

3 3-mm iron sheet m2 10 250,000.00 2,500,000.00

4 Normal brick Brick unit 4000 450.00 1,800,000.00

5 Cement Ton 1 750,000.00 750,000.00

6 Sand Trip 1 200,000.00 200,000.00

7 Kiln residues Trip 1 500,000.00

8 Delivery Trip 1 900,000.00 900,000.00

II Total

Total 20,250,000.00

Situation of burning trial:

After finishing the kiln, the research team dried it in one day, then performed

the first burning trial:

o During burning trial, the research team often exchanged with many people with

much experience in producing brick and ceramic to identify accuracy of the

building techniques and draw experience for burning and burning technology.


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o Differences of products which are burned from different kinds of materials

(comparison made on periods of the kiln X4: an amount of 5,5m3 materials)

Kinds of

material

Kg of

loaded

material

Time of

burning

Time of

cooling

Rate of

productsNote

Drybamboo

knots 30%

1,5 tons 48 hours 72hours

30% Small amount of loadedmaterial, short time of burning,

low quality products (coal

temperature reach about

300oC)

Fresh

bambooknots

1,8 tons 72 hours 98

hours

22% Products are not evenly burnt

with quite low quality (about

400oC To charcoal)

Fresh and

smallpoles

2,5 tons 86-92

hours

98

hours

20% Products are evenly burnt with

good quality, temperatureinside the kiln is quite high:

(600oC To low quality

activated carbon)

The above table is based on realistic calculation in X4 and from the certificate of quality

control done by Quang Ninh company of quality verification. This table shows that:

- If the material for burning is bamboo knots, bottoms obtained from by-products of

chopstick and slats for flooring production, product quality will not be high because this

material is not equal in terms of freshness and age of culms, leading to not enough

temperature inside the kiln.

- However, this material is available and cheap so it could be used for producing charcoal

instead of wood coal (this could be a potential product replacing wood coal when this

production is being limited due to risk of deforestation and forest-fire from coal fire).

- If fresh and small bamboo poles are used as material for burning, coal can reach high

quality, with the temperature similar to that of activated carbon. This product can become

activated carbon, a product with very high value and demand (for exportation) through

one more step of activation. Despite the availability and not really high value of this

plant, it is necessary to make quick collection and careful selection to ensure both quality

and freshness.

Kiln X4-1

- Time of burning: 45 hours - Time of cooling: 4 days

- Amount of obtained products: 242 kg. (30% of the kiln is not usable, not burnt)


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Table of specific expense estimate

Details Unit Amount Unit price Total

Loaded material Kg 1,395 200 279,000

Time of burning +

cooling

Hour 141 hours

Labor of burning Labor 8 30,000 240,000

Firewood for burning Kg 350 200 70,000

Total expense 587,000

Obtained product Kg 240

+ State of product amount and quality:

Because the kiln stopped production one week earlier, the material for burning which is

mainly bamboo knot, top and root obtained from chopstick production has become dry by

30-40%. Therefore, the material for loading only weighs 1395 kg/5.5m3.

It is partly due to the fact that the kiln is still wet, because newly built. Another reason is

that after 43 hours of burning, due to lack of experience, the research team had the kiln

covered so soon. That leaves an amount of not yet burnt material (30% the total amount

of material). The obtained products weigh 240kg, equivalent to 17% of material (which,

by deduction, only reached about 300oC).

(After discussion to draw experience, the research team and workshop owners agreed

that: Only using bamboo bottoms as material for burning and it will be burnt until green

smoke and white powder are seen around the chimney).

Alternating material:

After gaining experience from the first burning period, there are changes as follows:

- Kilns X4-2: Root + 200kg fresh pole


Loaded material (root + knot) Kg 1,555 200 311,000.00

Time of burning + cooling Hour 205 -Labor of burning Labor 12 30,000 360,000.00

Firewood for burning Kg 600 200 120,000.00

Total expense 791,000.00

Obtained products Kg 368

- Because loaded materials are fresh bamboo knots + poles which weigh more than

that in X1, there is a higher amount of material compared to X1 (160 kg)


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- Due to experience gained from the previous one, the burning process is carried

out more perfectly; however, the temperature fails to reach maximum degree, that

leaves an amount of 10-15% material in the kiln undone and the obtained product

is 368kg = 23,7%, (This amount still includes some undone material which

released smoke while being burnt), the kiln only reached temperature of 350-400oC.

- Kilns X4-3: Material is fresh and small poles with thick wall


Loaded material (bamboo

bottoms + knots)

Kg 2,606 250

651,500

Burning + cooling time Hour 283 0

Labor for burning Labor 12 30,000 360,000

Amount of burnt firewood Kg 750 200 150,000

Total expense 1,161,500Obtained product Kg 564

- Burning material for kiln X4.3 is small poles which are older than 3 years with

thick wall, and completely fresh. Thus, the total amount of material loaded into

the kiln reached 2606 Kg, twice as much as it was in kiln 1.

- Due to fresh and old enough material and a longer time of burning, kiln 3

produces good quality. There is only 5% of those lying the bottom of the kiln

which is not burnt completely.

- Besides, 564kg of products reach high quality (checking quality in Quang Ninhshows that coal obtained from his kiln reaches the temperature of 600oC). Some

is up to 7800kj/kg (Material coal accepted in Japan and Korea is 6000-6500kj/kg)

b. Building kiln and carrying out trial in the workshop X1: Double kiln - Thien

Phu.

Construction of kiln 1 began after the first period of kiln X4 was finished (in order to

redesign the suitable appearance, wall and gate). Its wall is thicker than that of X4 by

15cm; the gate for loading material is different of the burning gate:

- Size of the kiln:

+ Inside: 2 x (2.5 x 1.5 x 1.5 m)

+ Outside: 4 x 5.4 x 1.8 m

- Structure:


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+ The first layer: 24 cm fire-resistant brick

+ The second layer: glass wool of 5 cm thickness

+ The third layer: kiln residues of15 cm in thickness.

+ The forth layer: normal brick for kiln wall of 21 cm thickness.

+ Parabolic-shaped dome in 4 layers with domed frame made of iron.

Table of construction fees ofanaerobic burning kiln(double kiln)


I Materials 28,030,000.00


Glass liquid Kg 200 2,500.00 500,000.00

2 Asbestos fiber kg 300 10,000.00 3,000,000.00

3 3-mm iron sheet m2 18 250,000.00 4,500,000.00

4 Normal brick Brick unit 7000 500.00 3,500,000.00

5 Cement Ton 2 750,000.00 1,500,000.00

6 Sand m3 8 80,000.00 640,000.00

7 Kiln residues m3 8 80,000.00 640,000.00

8 Delivery Trip 1 1,500,000.00 1,500,000.00

II Total

Total 33,400,000.00

State of burning trial :

Specific detail of first burning cycle of X1 kiln (X1-1)

Details Unit Amount

X1 .a X1.b Total

Unit

price

Total

Loaded material Kg 1,405

1,610

3,015 200603,000

Time of burning + cooling Hour 183 182 183 0

Labor for burning Labor 14 14 30,000 420,000

Firewood for burning Kg 450 450 900 200 180,000

Total expenses 1,203,000


+ State of product amount and quality:

The material used for loading is bamboo bottoms, knots obtained from chopstick

production but fresher than that used in X4 (its moisture content decreases by 20-

25%), so kiln Thien Phu reaches the weight of 3100kg/11m3.

- In the kiln 1.a (one of both kiln), material used is thin bamboo top knots, so

that the material loaded into the kiln only weighs 1450 kg.

- In the kiln 1.b, material used is thick bottoms and knots, so that the material

loaded into the kiln reaches a higher weight, by 1610kg


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Due to early coverage of the kiln, there is amount of non burnt material (20-30%),

coal quality is low, obtained product amount is small (only 450 kg = 15%

material).

Alternating material:

Thanks to experience gained from the first burning period, there are changes in

the next periods as follows:

Kiln X1- cycle 2: Fresh bamboo ends

Details Unit Amount

A B Total

Unit

price

Total

Loaded material Kg 2100 2000 4100 200 820000

Time of burning +

cooling

Hour 231 219 231

0

Labor for burning Labor 14 14 14 30000 420000

Firewood Kg 620 570 1190 200 238000

Total expense 1478000

Obtained products Kg 290 270

o Materials used are completely fresh bamboo ends with thick wall, so there is a

great amount of loaded material; however, it takes time to complete burning (50

hours longer than cycle1).

o Age quality of bamboo poles are not equal, there are still many tender, spongy

poles which make products at low quality.

o Despite longer burning time than kiln 1, too thick wall leads to many non burnt

materials, of which the rate is rather high (25-30%) with the temperature inside

the kiln of only 450oC.

Kiln X1- Cycle 3: Fresh bamboo poles type 3-4 (circumference < 27-30 cm)

Details Unit Amount

A B Total

Unit price Total

Loaded material Kg 1850 1800 3650 200 730,000


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Time of burning +

cooling

Hour 207 196 207

Labor for burning Labor 14 14 14 30000 420,000


Total expense 1,356,000

Obtained products Kg 330 320 650

o Thanks to experience gained from the 2 previous kilns (cycles), the material of

kiln 3 was completely burnt. Only 10% of poles lying in the kiln bottom is not

completely burnt (due to the too high design of the chimney gate and lack of an

iron support in the kiln bottom).

o Product rate of kiln 3 reaches up to 18% excluding the non burnt part. Quality

obtained is high, with the temperature inside the kiln of 550oC (by deduction).

Kiln X1- cycle 4: Thick bamboo luongends and knots which are split into laths

Details Unit Amount

A B Total

Unit

price

Total

Loaded material Kg 2000 2000 4000 200

Time of burning +

cooling

Hour 289 284 289

Labor for burning Labor 14 14 14 30000Firewood for burning Kg 650 600 1250 200

Total expense

Obtained product Kg 357 408 765

o After discussion and experience exchanges, the team decided to have kiln X1 gate

lowered by 10 cm

o Place the iron support in the kiln bottom so that the internal temperature can reach

the material layer lying in the bottom.

o Based on experience of handicraft workers, the team waited until white smoke

was seen around chimney wall to have the kiln covered (combustion stopped).

o All of the above aspects help to gain better quality of product than kiln 3 with

product rate of over 19% (excluding the non burnt part).

Kiln X1-5: Bamboo luongends and knots


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Details Unit Amount

A B Total

Unit

price

Total

Loaded material Kg 2100 2000 200

Time of burning +

cooling

Hour 318 301 318

Labor for burning Labor 15 15 15 30000

Firewood for burning Kg 550 500 200

Obtained product Kg 400 390

o Product rate of kiln X1.5 reaches nearly 20% of loaded material, coal quality

reaches activated carbon at low level (about over 600oC).

o This is the kiln with highest quality compared to other kilns due to the experience

gained from the previous ones.

o After discussion, the team and workshop decided to leave one of two kilns (A) for

burning trial a second time, in order to study activation capacity of the kiln:

Kiln X1 cycle 5 . A - Second burning cycle

Details Unit Amount Note

Loaded material (charcoal) Kg 400 From kiln X1-5.a

Time of burning + cooling Hour 102 30+72

Labor for burning Labor 3

Firewood for burning Kg 200


To examine the activation capacity in the kiln (second burning cycle), the research

team carried out:

i. Coal gained after burning of kiln X1-5.A was left untouched in the kiln, the gate

was largely open so that the water stream can be absorbed in 3 days before re-burning.

ii. Carrying out 30 hours of continuous burning so that charcoal can interact with

water stream (H2O) and carbon dioxide (CO2) released from burning period at

high temperature (kiln temperature) then covering for cooling in 3 days.


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After unloading, according to visual comments of the team and workers of burning:

Coal gained after re-burning is blacker, more spongy and lighter; however, it is

necessary to have specialists to reexamine the accurate quality.

c. Establishment and burning trial of X5: carried out after first periods of kilns X4 and

X1 and after visits to workshops and traditional kilns in Lam Dong:

Establishment: Kiln X5: After 2-3 periods of burning carried out in kilns X1 and X4

together with experience gained from visits to kilns of coal burning of Da Lat

company of urban sanitation and advices of some experts, there are changes in

establishment of kiln X5 as follows:

o Kiln was built in round (elliptical) shape high dome.

o Kiln volume is bigger than that of kiln X1 and X4 (11m3/1 kiln)

o One of the two kilns was built with only one layer of fire-resistant brick and

especially:

After the research visit in Lam Dong, the research team realized that:

Each ton of material can produce 6-8% attar (essential oil) (equivalent to

60-80kg attar), an important income source in the process of coal burning.

Bamboo attar is a product with high economic value (price of exporting

from China to Japan and Korea is about 1.2 USD selling price inVietnam is about > 10,000 VND/kg).

And market demand (in Japan, Korea) is very high ( buy all if available

said staff of Da Lat company of managing urban facilities)

Design of the extracting system is simple, and experts from Da Lat

company met, give enthusiastic instructions on extracting technology.

Therefore, the team decided to design a pilot system for bamboo attar

production in kiln X5:

Size of the kiln:

+ Inside: 2 x (3 x 2 x 2) m

+ Outside: 4.4 x 5.7 x 2 m

- Structure:

+ The first layer: 24 cm of fire-resistant brick


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+ The second layer: glass wool of 10cm thickness.

+ The third layer: kiln residues of15cm thickness.

+ The forth layer: normal brick for kiln wall of 21 cm thickness.

+ 4- layer dome built in parabolic shape with iron frame.

+ Attar (vinegar) extracting system with china (porcelain) pile of150


I Materials


Glass liquid Kg 300 3,500.00 1,050,000.00

2 Asbestos fiber kg 400 10,000.00 4,000,000.00

3 3 mm iron sheet m2 20 250,000.00 5,000,000.00

4 Normal brick Brick unit 8000 500 4,000,000.005 Cement Ton 3 750,000.00 2,250,000.00

6 Sand Trip 2 200,000.00 400,000.00

7 Kiln residues Trip 1 1,000,000.00 1,000,000.00

8 Delivery Trip 2 1,500,000.00 3,000,000.00

II Labor 5,150,000.00

Total(I+II) 41,600,000.00

Specific details of burning the kiln

Kiln X5- Cycle 1 :

Details UnitAmount

A B Total

Unit

priceTotal

Loaded material Kg 2600 3100 200

Time of burning +

cooling

Hour 148 157 157

Labor for burning Labor 20 20 20 30000

Firewood for burning Kg 750 900 200

Attar (vinegar) Kg 76 100 176

o It is the first time of extracting attar without much experience; on the other hand,

about 20% of loaded material as bamboo ends and knots is dry, these two elements

lead to not high amount of obtained attar; however:


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o Attar quality gained can meet exportation standard based on examine instruction of

Da Lat company of managing urban facilities (pH level ranges from 3 to 4).

o This amount of attar was sent as offer to several companies, among which a company

based in Lao Cai (owned by Mr. Dan) agreed to buy at the price of 10.000 VND/kg;

Mr. Dan promised to visit the workshop and apply for purchasing of all the attar

extracted by us.

3. Conclusion:

By April 30th, 2007, all the 3 workshops (X1, X4 and X5) had kilns built and 8 burning trial

have been carried out. After burning, each place had exchange of experience performed

between the research team and workshops owners, therefore:

o Coal quality is always improved kiln after kiln.

o Up to May 30th

2007, all workshops owners had mastered fundamental techniques ofburning and monitoring methods for the highest quality.

o In the last 4 kilns (cycles) in workshops X1 and X4, coal quality reaches at least 600oC

(samples of X4-3 have been sent for examination) equivalent to temperature to obtain

quite low quality activated carbon (>600oC).

o In kiln X1-5, the second period of burning trial was carried out with success and produces

high activated carbon: coal then produced is black, spongy, light (of course, it will be sent

for examination of quality)

o In kiln X5, attar extracting was carried out and produced 176 kg attar (vinegar) with

accepted quality which was sent as offer and accepted by customer at the price of

10.000VND/kg (now pending for order from customers so that mass production (in large

amount) can be carried out)

3.1 Comments on production expense and investment

a. Investment efficiency

o According to INBAR guidance disseminated in Internet together with requirements

on product quality, the research team sees that investment in establishment of kiln and

burning trial in workshops of the project is completely possible and beneficial:

At the rate of 1/5 (5 kg material can produce 1 kg product) in coal production,

even not mention attar extracting it can make profit (even selling charcoal at

2.500/kg),


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However, for effective production, it is necessary to produce coal with high

quality for consumption in exporting market: the lowest exporting price from

Chinese enterprises to Japan and Korea market is currently 0.6 USD CIF/kg for

normal bamboo coal.

If bamboo attar (vinegar) is added to final products, we will have more 2,000,000-

3,000,000 VND/5 tons of bamboo. (200-300kg attar) therefore, with the domestic

selling price of 2000 VND/kg bamboo coal, we can gain total revenue on 6 tons

of bamboo (including firewood) of from 4,000,000-5,000,000 VND, in which

total production expense is only 2,000,000 VND (if end knots are used as

material) and 3.500.000 VND (if tender bamboo plants are used as material).

b. Related impacts:

Producing bamboo coal in Vietnam, especially in mountainous area of Thanh

Hoa, can serve as an appropriate business method because it helps workshops take

complete advantage of waste from chopstick, handicraft and flooring laths

production (currently 40-60% is waste).

Additionally, there is much amount of small bamboo luong plants with low

economic value which are often sold for column (pole) at 200-300 VND/kg. This

kind of material is small but firm and has high life-expectancy (over 3 years), so it

is very suitable for production of high quality coal. If this material is taken

advantage for coal burning, it can bring about high economic value (exportation)

to increase income of luong planters.

c. Possibility of implementation in a larger area:

All of the materials used in kiln building are produced and sold in large amount

nationwide, and can be easily purchased. Their price is not high (see details at the

table of kiln building expense)

Especially, after visiting Lam Dong where there are many households producing

activated carbon and charcoal from similar kilns using Japanese technology, the

research team sees that: it is possible to reduce cost of kiln building, if we can

take advantage of land position of the mountainous area to remove some layers

but still ensure kiln and coal quality:

Currently kiln X5 with the volume of 11m3, total building expense is about

25,000,000 VND (double kiln in X5 costs 41,600,000 VND)


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If removing fire-resistant layer, each kiln with the volume of 10M3 only costs

10-12,000,000 VND.

If digging a deep hole to build the kiln and only building a refractory layer,

each kiln with the volume of 10M3 only costs 16-17,000,000 VND.

Due to un-complicated technology of burning which can be transferred,

together with the above estimated costs, it is possible to make application

of coal burning technology at household level (group of households) (even

including household with average income and nearly-poor households)

d. Production expense

o After two first period of drying as well as testing for experience, from the third one,

technology of burning has been perfected, burning kiln produces high quality coal,

product rate is 22% (1 ton of fresh bamboo produces 220kg coal + 20-30kg attar).Coal burning can bring about high economic efficiency:

o Kiln X4- Cycle 3 for ex. (have had quality examined)


Loaded material Kg 2500 300 750,000

Labor for burning Labor 8 30000 240,000

Firewood for burning Kg 500 200 100,000

Kiln depreciation /cycle 1 87.000 87.000

Total expense 1,177,000

Obtained product VND 2.250,000

Coal 500 2500 1,250,000

Attar Kg 100 10.000 1.000,000

Profit (if completely sold) 1.073.000

o The above table is based on charcoal selling price in domestic market at lowest price

(selling to Truong Phat activated carbon incorporated company - Bac Giang - this

price has excluded delivery cost). The value can greatly increase through exportation.

(0.5 US/kg FOB Hai Phong)

3.2. Difficulties and risks (lessons of experience):

- This kiln is an anaerobic kiln with round shape, domed roof. This kiln can ensure

tightness and endurance against push of pressure inside the kiln (caused by pressed


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air in burning process). Therefore, skilled workers are needed for the construction, if

there is any mistakes, it can lead to state of uncovered, cracked and even collapsed.

- If the chimney is too large, heat can be released quickly and conversely. These two

states will lead to low quality of product (appropriate size of chimney: 7-10cm in

height; 40cm in length).

- If the kiln is covered too soon, there will not be enough heat that leads to low quality

of product. If the kiln is covered too late, coal will be spoilt, leading to waste of

material and fuel.

- Due to a characteristic of bamboo coal of good absorbability, after a long time, this

product will absorb humidity in the air that leads to low quality. Therefore, it needs

storing in a dry and close environment so that it can not absorb humidity in the air.

3.3 Experience and considerations in terms of technology and techniques:

a. In terms of construction:

The kiln used for coal burning is anaerobic kiln which can resist heat and

burn coal under method of heat distribution. Therefore, it requires that the

following aspects should be ensured:

- Totally close: in order to prevent air circulation as well as heat from releasing

in the process of burning and cooling.

- Heat resistant (refractory): in the process of burning and cooling,

temperature inside the kiln can reach over 1000oC, so kiln structure should

have high capacity of heat-resistance, otherwise phenomenon of crack and

damage can occur.

- Quickly heat absorbent: because temperature and quality of coal will

completely depend on kiln temperature, the inside wall the kiln must have the

capacity of not only absorbing heat but also quickly absorbing heat so that

kiln temperature can reach highest degree in the process of burning and

cooling.

- Resistant against internal pressure: during burning and cooling, because the

kiln is completely close and the inside temperature quickly increases, the air

in the kiln is quickly elastic that creates a very strong push from inside.

Therefore, to ensure that the kiln is not cracked, broken or even exploded, the

kiln wall structure must be really thick and firm (metal support structure


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bearing high pressure should be placed in kiln wall and top at the end of

building process).

b. In terms of burning technology:

The process of coal burning consists 7 steps in all:

Selecting material for loading: For products with high quality, materials

selected should be fresh poles or fresh end knots of plants aged more than 3

years and not spongy.

Drying: there is white smoke in this process (like colour of water).

Pre-heat distribution: in this process, smoke is yellow, then changes into

black and returns to yellow (this is also time of attar extracting).

Activation: the smoke will change from light white into blue white. At the

end of this process, white powder will dry water around the chimney opening

that leads to the state that white powder is seen around chimney opening as

smoke ash. This is the time for covering (cover the chimney opening first, kiln

gate later)

280~450

Loading

Over 450

60

150~280 ~450

DryingActivation

Pre-heat distribution

Refining coal at high

temperature

CoolingUnloading - Cleaning

Packing

120~150


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Coal refining: while the kiln is being covered, coal is still in the process of

heat distribution and heat release => kiln temperature continues to rise, if the

kiln is completely close, at the end of this process, it can reach 1000oC.

Cooling: after 3 days of refining, the kiln can be left gradually cool, or to

make it quickly cool, they use cool water to continuously spill its top.

Unloading: when the temperature decreases below 60C, coal can be

unloaded, then we clean soot on coal then process and pack as required by

customers.

4. Proposals

Although bamboo luong value chain has been developing and tends to completely alternate

wood coal sector in many countries in the world, especially in Japan, Korea, Taiwan, China

and European developed countries, its still a new sector in Vietnam, not only for customers

but also for producers. Therefore, there still exists great challenges in techniques of kiln

building and technology of coal burning for those who want to participate in this sector.

Currently there are 2 workshops producing bamboo coal in small scale (one in Hoa Binh,

another in Vinh Phuc), with different techniques of building burning kiln. There are some

bases and individuals who are studying with the expectance to participate in this new and

potential sector. They are also studying techniques of building and technology of burning

from many different sources.With experiences gained from trial process, the research team makes some proposals as

follows:

4.1 Proposals in terms of construction:

There are 2 kinds of kiln that can be used for burning bamboo coal

Normal kiln - producing low quality coal - this kind of kiln can be built by local

farmers or inhabitants because the construction techniques arent complicated and

it can be used for burning any type of material.

- This is an anaerobic kiln without refractory material: used for burning mixed

materials of which age and quality can not be identified (end knots, by-

products, wastes from chopstick and toothpick production) - these kinds of

material hardly produce products with high quality and high selling price.


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- For this kiln, in the process of burning, the temperature inside can not exceed

500-600oC so normal brick mixed with soil can be used to build the wall

inside the kiln, while brick, sand and normal cement can be used to build the

surrounding wall.

- With the above structure, 01 kiln with the volume of 10m3 only costs

12.000.000 VND for construction expenses.

Refractory kiln - producing high quality coal - activated carbon - this kind of

kiln should only be built by enterprises or concentrated workshops due to many

advanced techniques:

- This kind of kiln has the capacity of high heat accumulation and resistance so

refractory brick, glass wool and glass liquid are necessary materials for

construction.

- Each refractory kiln with the volume of 10m3 costs a bit higher than

30.000.000 VND for construction expenses.

Both of the above kilns can be built by two ways:

- Form 1: Kiln wall has rectangular shape with dome - an advantage of

this kind of kiln is its firm structure, easily built but limited in the

capacity of heat accumulation.

- Form 2: Kiln wall has round or elliptical shape with dome - this kind

of kiln has an advantage of higher heat accumulation but skilledworkers are required for construction.

To ensure closeness as well as heat accumulation, both of the above kilns

must be built with really thick wall (as thick as possible).

Kiln wall is divided into 3 layers - each layer is 20-25cm thick:

- The first layer: made from fire-resistant material or dense brick.

- The second layer: made from kiln residues mixed with soil.

- The third layer: made from brick - cement - sand as a surroundingwall.


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- It is necessary to carry out building trial of 2 kilns of normal kind (without

refractory material) for examining and testing the possibility of developing

this kind of kiln in the community.

- It necessary to supplement a system of attar extracting for all kilns to take

complete advantage of products.

- Carrying out building trial of a kiln producing high quality activated coal

(self-activating through a steaming system or carbon dioxide in the close

refining process)

4.2 Proposals in terms of burning techniques

Material should be as fresh as possible (high humidity content).

In the process of burning, workers have to continuously monitor smoke state to

accurately identify coal state in the kiln.

Kiln should be covered only when, or right after, white powder is seen around the

chimney.

Carrying out production trial of high quality activated coal (self-activating

through a second burning or a steaming system or carbon dioxide in the close

refining process)


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Annex

Kiln X4- cycle 2:bamboo ends +200kg fresh pole

Details Unit AmountUnit

priceTotal

Loaded material Kg 1555 2

00 311,000.00

Time of burning + cooling Hour 205 -

Labor for burning Labor 12 30,0

00 360,000.00

Firewood for burning Kg 600 2

00 120,000.00

Pack Piece 25 1,500 36,800.00

Deduction KG 368

60 22,080

Total expense VND 849,880.00

Obtained product VND 1,161,500.00

Coal kg 368 2,0

00 736,000.00

Attar (4% total material) kg 62 10,0

00 622,000.00

Net profit 311,620.00

Kiln X4- cycle 3: fresh small bamboo poles with thick wall

Loaded material Kg 2606 2

50 651,500.00


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Time of burning + cooling Hour 283 0.00

Labor for burning Labor 12 30,0

00 360,000.00

Firewood for burning Kg 750 2

00 150,000.00

Pack Piece 38 1,5

00 56,400.00

Deduction KG 564

60 33,840

Total expense VND 1,161,500

Obtained product VND 2,170,400

Coal kg 564 2,0

00 1,128,000

Attar (4% total material) kg 104 10,0

00 1,042,400

Net profit 1,008,900.00

Kiln X1- cycle 3: Fresh bamboo poles type 3-4

Details Unit Amount

A B Tota

l

Unit

price

Total

Loaded material Kg 1

850

1

800

3650 200

730,000Time of burning + cooling Hour 207 196 207 0

Labor for burning Labor 14 14 14 30000 420,000


Pack Piece 43 1500 65,000

Deduction KG 650 100 65,000

Total expense VND 1,486,000


Coal kg 330 320 650 2,0

00 1,300,000

Attar (4% total material) kg 74 72 146 10,000 1,460,000

Net profit VND 1,274,000

Kiln X1- cycle 4: Laths of thick bamboo luong knots

Loaded material Kg 2 2 4000 200 800


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000 000 ,000

Time of burning + cooling Hour 289 284 289

-


0,000

Firewood for burning Kg 650 600 1250 200 25

0,000

Pack Piece 51 1500 7

6,500

Deduction KG 765 100 7

6,500

Total expense VND 1,62

3,000


Coal kg 357 408 765 2,0

00

1,53

0,000

Attar (4% total material) kg 80 80 160 10,0

00

1,60

0,000


Kiln X1- cycle 5: Bamboo luong ends and knots

Loaded material Kg 2

100

2

000

4100 200 82

0,000

Time of burning + cooling Hour 318 301 318

-


0,000

Firewood for burning Kg 550 500 1050 200 21

0,000

Pack Piece 53 1500 7

9,000

Deduction KG 790 100 7

9,000

Total expense VND 1,63

8,000


Coal kg 400 390 790 2,0

00

1,58

0,000

Attar (4% total material) kg 84 80 164 10,0 1,64


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00 0,000


Rate of attar extracting estimated on material of end knots (20% of them is

dry) is 4%.

Rate of attar extracting estimated on material of complete fresh poles is 7%.

Domestic selling price of charcoal is 2000 VND/kg (excluding delivery cost).

Selling price of attar to exporting companies is 10.000 VND/kg.

According to the above detailed tables: if charcoal produced is only for sale in domestic

market, it is necessary to extract attar for economic benefits (it can be much higher through

exportation)

Documents

Charcoal Production Trial MPDF GRET Report 1 120607-2