Use of wastes and by-products

The Japanese cement industry has developed technologies that enable the use of wastes as alternative raw materials or alternative thermal energy. It leads to save natural resources and extend the life of existing landfill sites.

Transition of amount of used wastes and by-products in Japan

  Figure 1 shows the types of used wastes and by-products in Japanese cement industry.
  The transition of the cement production, the total amount of used wastes and by-products and the specific amount of used wastes and by-products are shown in Figure 2. The specific amount of used wastes and by-products was 251 kg/t-cement in FY1990. But, it has increased year by year. In FY 2016 it was 474 kg/t-cement and the used total amount was 28.0 million tons.


Figure 1 Uses of wastes and by-products in Japanese cement industry

Figure 2 The transition of cement production, wastes and by-products, and the specific amount of wastes and by-products used in cement production

Table 1 shows the transition of the used amount of wastes or by-products by types.
  The amount of blast furnace slag is the total of granulated blast furnace slag and air-cooled blast furnace slag.
  The granulated blast furnace slag is mainly used for admixture of Portland blast furnace slag cement and the air-cooled blast furnace slag is used for one of raw materials of clinker.
  Figure 3 shows ratio of used amount in cement industry to amount of blast furnace slag from steel works. In FY 2015, the rate was 30.1 percent.
  The amount of coal ash is the total of fly ash and clinker ash. The produced amount of Portland fly ash cement in specified by JIS R 5213 was only 115,000 ton in FY 2016, and the ratio of Portland fly ash cement to total amount of produced cements was only 0.22 percent. So, the coal ash is mainly used for a raw material of clinker in Japan. Figure 4 shows ratio of used amount in cement industry to amount of coal ash generated from power plants. In FY 2014, the rate was 65.0 percent.

Table 1 The amount of wastes or by-products used for cement production

(Units:thousand tons)

Type Use for1) 1990 2000 2010 2012 2013 2014 2015 2016
Coal ash ARM, MIC 2,031 5,145 6,631 6,870 7,332 7,407 7,600 7,597
Blast furnace slag ARM, MIC 12,213 12,162 7,408 8,485 8,995 8,065 7,301 7,434
Sludge ARM 341 1,906 2,627 2,987 3,206 2,970 2,933 3,052
By-product gypsum MIC 2,300 2,643 2,037 2,286 2,401 2,320 2,225 2,149
Waste soil from construction2) ARM 1,934 2,011 2,407 2,598 2,278 1,850
Incineration ash (excluding coal ash),Soot,Dust ARM 468 734 1,307 1,505 1,405 1,441 1,442 1,534
Non-ferrous slag ARM 1,559 1,500 682 724 770 723 722 757
Woodchips AF 7 2 574 633 657 696 705 642
Waste plastic AF 0 102 445 479 518 595 576 623
Foundry sand ARM 169 477 517 492 461 454 429 409
Steel slag ARM 779 795 400 410 423 421 395 405
Waste oil AF 90 120 275 273 273 264 293 324
Waste activated clay ARM 40 106 238 253 273 275 311 287
Recycled oil AF 51 239 195 189 186 171 179 195
Cullet ARM 0 151 111 143 148 157 129 141
Waste tire AF,ARM 101 323 89 71 65 58 57 69
Meat and Bone meal ARM 0 0 68 65 63 58 57 57
RDF,RPF3) AF 0 27 48 50 55 54 37 35
Coal mining waste ARM 1,600 675 0 0 0 0 0 0
Others 14 253 408 595 626 485 382 438
Total(thousand ton)   21,763 27,359 25,995 28,523 30,265 29,212 28,053 27,997
cement production(thousand ton)   86,849 82,373 55,902 59,310 62,241 60,956 59,074 59,114
Total /cement production(kg/t-cement)   251 332 465 481 486 479 475 474

Note 1) ARM : Alternative raw materials of clinker, MIC : Constituent of blended cement or Portland cement, AF : Alternative fuels

Note 2) “Waste soil from construction” has been categorized into “Others” before FY 2000.

Note 3) RDF: Refuse Derived Fuel, RPF: Refuse derived paper and plastics densified Fuel.

Figure 3  The ratio of used amount in cement industry to amount of blast furnace slag from for steel works
  Total amount used in FY2015 : 24.804 Mt
  Amount used for cement production : 7.474 Mt (30.1%)

[Source]
  “Annual report for iron and steel slag statistics”
  (published by Nippon Slag Association)

Figure 4  The ratio of used amount in cement industry to amount of coal ash generated from power plants
  Total amount generated in FY2014 : 9.403 Mt
  Amount used for cement production : 6.109 Mt (65.0%)

[Source]
Japan Fly ash Association

Transition of use of alternative thermal energy in Japan

  Wood chips, waste plastic, waste oil, etc.al are used as alternative thermal energy at burning process. Figure 5 shows the ratio of alternative thermal energy at burning process. Over the past several of years, the ratio has come to some 17%. And, wood chips and other waste have used as alternative thermal energy for on-site power generations Figure 6 shows the ratio of alternative thermal energy for on-site power generations.
  The use of alternative thermal energy contribute to save natural resources and extend the life of existing landfill sites.

Figure 5  Ratio of alternative thermal energy at burning process

Figure 6  Ratio of alternative thermal energy for on-site power generation

Extending the life of landfill sites

  In Japan, it is becoming difficult to find new landfill sites, because Japanese land area is very small. The cement industry has helped to extend the life of existing landfill sites by using industrial wastes. The estimated result of extending the life of existing landfill sites is shown as follows.

- The remaining capacity of industrial landfill sites in Japan at April 1, 2014 was 171,810,000 m3(A)*.
- The remaining life of industrial landfill sites was estimated to be 14.7 years(B)*.
- The annual volume of industrial waste disposed is estimated to be 11,688,000 m3(C=A/B).
- The volume of wastes and by-products taken by cement plants in FY 2014 is estimated to be 20,202,000 m3(D)**.
- If the cement industry will not use wastes and by-products at all, the remaining life of industrial landfill sites are estimated to be 5.4 years(E=A/(C+D)).

  The comparing of estimated value B(14.7 years) and estimated value E(5.4 years) shows that the use of large amount of wastes and by-products in Japanese cement industry surely helps to extend the life of existing landfill sites.

(*) Source : Ministry of the Environment
(**) This volume is estimated with the amount of wastes or by-products shown in Table 1 and these bulk densities.




 
 
   
 
 

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