Processes

The most widespread desulfurization process in the developed countries is the wet lime slurry method, whose byproduct is mostly pure gypsum. In the developing countries, on the other hand, a semi-dry process tends to be adopted, owing to its low construction and running costs. However, the byproducts from a semi-dry process contain Ca(OH)2 (calcium hydroxide), CaCO3 (calcium carbonate) and fly ash, as well as gypsum. Among several

Table 10.2. Salt composition of soil profile of Haplic Solonchak (non-alkali soil)

Depth

pH

TSS

co32

hco3-

ci

SO42-

Ca2+

Mg2+

NA+ + K+

ESP

(cm)

g/kg)

cmol/kg

soil

(%)

0-32

8.1

171.1

0.04

0.22

224.0

53.0

29.1

34.9

190.0

12.8

32-55

8.3

89.0

0.09

0.20

28.2

17.4

13.9

30.0

30.5

10.5

55-90

7.9

69.0

0.09

0.27

30.0

19.9

14.6

28.0

29.7

10.06

90-100

7.7

66.0

0.05

0.30

40.0

17.7

20.9

29.8

30.6

9.5

100-150

7.9

70.7

0.01

0.45

56.4

15.6

24.6

30.2

30.2

10.9

TSS; Total soluble salts;

ionic determination was done by water extraction in soil: water=1:5.

Table 10.3. Salt composition of soil profile of Alkali Solonchak

Depth

pH

TSS

co32

hco3-

ci

SO42"

Ca2+

Mg2+

NA+ + K+

ESP

(cm)

(g/kg)

cm

iol/kg soil

(%)

0-2

10.6

20.9

21.9

3.5

8.4

3.6

0.02

0.07

38.7

78.9

2-17

10.3

9.9

2.1

3.8

5.3

0.9

0.03

0.04

18.9

60.3

17-31

10.4

6.9

1.9

3.8

4.9

0.6

0.02

0.07

19.4

70.4

31-57

10.6

4.5

2.6

4.0

3.3

0.4

0.10

0.15

10.5

50.1

57-80

10.4

3.9

2.0

3.3

2.1

0.4

0.20

0.19

17.5

42.9

TSS; Total soluble salts;

ionic determination was done by water extraction in soil: water=1:5.

Fig. 10.2. Concept of reclamation of Alkali soils by calcium sulfate.

semi-dry processes, the byproducts from the ash recovery activation method (ARAM) were examined, because the Japanese government has already installed a working plant at Qingtao City, Shandong province in China. ARAM is the process by which a slurry of the polycrystal substance called Ettringite, which is formed through hot water treatment of a mixture of CaO (calcium oxide), fly ash and gypsum, is sprayed into the flue gas to absorb SO2 (sulfur dioxide) as gypsum.10 The chemical properties of byproducts from desulfur-ization processes are shown in Table 10.4. The byproduct from the wet process is almost pure gypsum, while the byproduct from the semi-dry process includes only 20 wt % gypsum and 20 wt % calcium hydroxide, which would increase the pH of the soil.

Until now, there have been very few applications of the byproduct from the semi-dry process to the alkali soils in China, because it is considered to be only waste.

Organic Gardeners Composting

Organic Gardeners Composting

Have you always wanted to grow your own vegetables but didn't know what to do? Here are the best tips on how to become a true and envied organic gardner.

Get My Free Ebook


Post a comment