In a recent blog, I made some comments on the US market for
waste to energy (WTE) plants. (Click
here to read that blog.) In this blog,
I provide some comments on metal recovery in the bottom ash, which results from
incinerating waste at WTE plants.
The comments are based on data and information I have found
on the Internet and some assumptions I have made in using data to make
conclusions.
The following table (Table 1) shows for three regions, the United
states (US), the European Union (EU), and Japan (JA), an estimated recent total
bottom ash in millions of metric tonnes (mt) generated by WTE plants in those
regions (column 6):
Table 1
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Col 1
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Col 2
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Col 3
|
Col 4
|
Col 5
|
Col 6
|
MSW amt m mt
|
% wte
|
amt wte m mt
|
% bottom ash left
|
amt bottom ash left m
mt
|
|
US
|
264
|
0.095
|
25.08
|
0.25
|
6.27
|
EU
|
250
|
0.205
|
51.25
|
0.25
|
12.8125
|
JA
|
63.4
|
0.75
|
47.55
|
0.25
|
11.8875
|
individ. wte plant
incinerating 1 million MSW/yr
|
1
|
1
|
1
|
0.25
|
0.25
|
The total bottom ash in millions of metric tonnes (mt)
(column 6) is based on the following:
1. The total
municipal solid waste (MSW) amounts generated in each region (column 2). These amounts were computed by multiplying the
population of the region (US – 319 million; EU – 503 million; and JA – 127
million) by the estimated per person day-generated waste in each region (US – 5
pounds per day; EU - 3 pounds per day; and JA – 3 pounds per day). The total MSW amounts are given in column 2.
2. The percentage of
this total waste for each region that is incinerated at WTE plants (US - 9.5%;
EU – 20.5%; and JA – 75%). This percentage
is given in column 3.
3. The total amount (in
million mt) of incinerated waste for each region. This amount is generated by multiplying column
2 by column 3 and shown in column 4.
4. The percentage of bottom
ash left from incinerating the WTE waste.
Twenty-five percent is an average and this amount is shown in column 5.
Column 4 times column 5 gives the amount of total bottom ash
in millions of metric tonnes for each region (column 6).
Also in Table 1 is the estimated amount (250,000 mt) of
bottom ash generated from one WTE plant incinerating one million mt of waste
per year.
Using the bottom ash amounts (column 6) in Table 1, the
following 3 tables were generated:
Table 2
US
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Col 1
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Col 2
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Col 3
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Col 4
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Col 5
|
Col 6
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Col 7
|
Col 8
|
Col 9
|
mt bottom ash
|
% metal in bottom ash
|
mt metal
|
recover %
|
mt metal recover
|
$/mt at LME
|
total market value
before smelter
|
sales price - 60% of
market value
|
|
al
|
6,270,000
|
2.0%
|
125,400
|
55%
|
68,970
|
1550
|
$
106,903,500
|
$
64,142,100
|
cu
|
6,270,000
|
0.5%
|
31,350
|
55%
|
17,243
|
5140
|
$
88,626,450
|
$
53,175,870
|
steel
|
6,270,000
|
8.0%
|
501,600
|
85%
|
426,360
|
120
|
$
51,163,200
|
$
30,697,920
|
ss
|
6,270,000
|
0.3%
|
18,810
|
55%
|
10,346
|
1830
|
$
18,932,265
|
$
11,359,359
|
zn
|
6,270,000
|
0.2%
|
12,540
|
55%
|
6,897
|
1810
|
$
12,483,570
|
$
7,490,142
|
totals
|
$
278,108,985
|
$ 166,865,391
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||||||
Table 3 EU
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||||||||
Col 1
|
Col 2
|
Col 3
|
Col 4
|
Col 5
|
Col 6
|
Col 7
|
Col 8
|
Col 9
|
mt bottom ash
|
% metal in bottom ash
|
mt metal
|
recover %
|
mt metal recover
|
$/mt at LME
|
total market value
before smelter
|
sales price - 60% of
market value
|
|
al
|
12,812,500
|
2.0%
|
256,250
|
55%
|
140,938
|
1550
|
$
218,453,125
|
$ 131,071,875
|
cu
|
12,812,500
|
0.5%
|
64,063
|
55%
|
35,234
|
5140
|
$ 181,104,688
|
$ 108,662,813
|
steel
|
12,812,500
|
8.0%
|
1,025,000
|
85%
|
871,250
|
120
|
$
104,550,000
|
$
62,730,000
|
ss
|
12,812,500
|
0.3%
|
38,438
|
55%
|
21,141
|
1830
|
$
38,687,344
|
$
23,212,406
|
zn
|
12,812,500
|
0.2%
|
25,625
|
55%
|
14,094
|
1810
|
$
25,509,688
|
$
15,305,813
|
totals
|
$
568,304,844
|
$ 340,982,906
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Table 4 JA
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Col 1
|
Col 2
|
Col 3
|
Col 4
|
Col 5
|
Col 6
|
Col 7
|
Col 8
|
Col 9
|
mt bottom ash
|
% metal in bottom ash
|
mt metal
|
recover %
|
mt metal recover
|
$/mt at LME
|
total market value
before smelter
|
sales price - 60% of
market value
|
|
al
|
11,887,500
|
2.0%
|
237,750
|
55%
|
130,763
|
1550
|
$
202,681,875
|
$ 121,609,125
|
cu
|
11,887,500
|
0.5%
|
59,438
|
55%
|
32,691
|
5140
|
$
168,029,813
|
$ 100,817,888
|
steel
|
11,887,500
|
8.0%
|
951,000
|
85%
|
808,350
|
120
|
$
97,002,000
|
$
58,201,200
|
ss
|
11,887,500
|
0.3%
|
35,663
|
55%
|
19,614
|
1830
|
$
35,894,306
|
$
21,536,584
|
zn
|
11,887,500
|
0.2%
|
23,775
|
55%
|
13,076
|
1810
|
$
23,668,013
|
$
14,200,808
|
totals
|
$
527,276,006
|
$ 316,365,604
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These tables are used to generate the sales prices of five
metals (al – aluminum; cu – copper; steal; ss – stainless steel; and zn – zinc),
which can be recovered from the generated bottom ash. A table is provided for each of the three
regions. Column 9 gives the sales
prices.
In each table, column 2 comes from column 6 in Table 1. Column 3 is the estimated percentage amount
of the metal in the bottom ash. The
estimated metal amounts (column 2 times column 3), in mt, are provided in
column 4. Column 5 is the estimated
recovery percentages of the metals in the bottom ash, and column 6 is the potential
amounts of the metals that can be recovered (column 4 times column 5). Column 7 is a recent (August 2015) price per
mt for the metals, found at the London Metal Exchange (LME) website. Multiplying column 6 times column 7 gives a
recent total market value (column 8), before smelter operations, of five metals
that can be recovered from the bottom ash.
Column 9 gives the estimated sales price of the recovered metals
at the WTE plants. The plants need to sell
the metal to smelters for further processing to pure metal. It is assume that the smelters will pay the
WTE plants 60% of the market value in order to cover their costs and make a profit
when the smelters sell the metals.
Many of the assumptions used above, e.g. the percentages of total
MSW sent to WTE plants in each region; the percentages of the incinerated waste
remaining as bottom ash; the percentages of metal in the bottom ash; and the percentages
of metals that can be recovered from the bottom ash are based on my studying
and interpreting European data, information, and comments. The European Union has been active in developing
WTE technology for many years and has more than 470 WTE plants. By comparison, the US has about 85
plants. Europe has conducted much study
of the technologies and problems in WTE processes, and much can be found on the
internet on what they have learned.
Metal recovery amounts from WTE bottom ash depend on many
factors that frequently vary from WTE to WTE plant and over time. So, often only ranges of data, e.g. the percentages
of total MSW sent to WTE plants and the percentages of incinerated waste
remaining as bottom ash, can convey, correctly, correct amounts. For those percentages used in the above tables,
I have selected a mid-value of the ranges that I have found in the European
data.
From the above 3 tables, the approximate total value of the
five metals recoverable from bottom ash for all three regions is $1.4 billion
(US - $278 million; EU - $568 million; and JA - $527 million).
Perhaps more useful is the data provided in the following
table:
Table 5 One WTE Plant Incinerating One Million MT MSW/Year
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Col 1
|
Col 2
|
Col 3
|
Col 4
|
Col 5
|
Col 6
|
Col 7
|
Col 8
|
Col 9
|
mt bottom ash
|
% metal in bottom ash
|
mt metal
|
recover %
|
mt metal recover
|
$/mt at LME
|
total market value
before smelter
|
sales price - 60% of
market value
|
|
al
|
250,000
|
2.0%
|
5,000
|
55%
|
2,750
|
1550
|
$
4,262,500
|
$
2,557,500
|
cu
|
250,000
|
0.5%
|
1,250
|
55%
|
688
|
5140
|
$
3,533,750
|
$
2,120,250
|
steel
|
250,000
|
8.0%
|
20,000
|
85%
|
17,000
|
120
|
$
2,040,000
|
$
1,224,000
|
ss
|
250,000
|
0.3%
|
750
|
55%
|
413
|
1830
|
$
754,875
|
$
452,925
|
zn
|
250,000
|
0.2%
|
500
|
55%
|
275
|
1810
|
$
497,750
|
$
298,650
|
totals
|
$
11,088,875
|
$
6,653,325
|
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Table 5 show results similar Tables 2, 3, and 4 except the
results are for a single WTE plant incinerating approximately one million mt of
waste per year. Table 5 shows an
estimated sales price for the recovered metals of $6.7 million, an estimated
amount that the plant might obtain from recovering the five metals out of its
bottom ash.
The technology for recovering the five metals from bottom
ash has been under development for some time, and is fairly advanced and used
in several WTE plants. However, the technology
continues to be improved, so that the recovery processes should become even
more successfully applied. The benefits
for recovering metals from bottom ash includes not just revenues that can
exceed the recovery process costs but
also other benefits such as environmental benefits.
A good overview of recovering metals from bottom ash is
found in a report entitled “Recovery of Metals from Waste Incinerator Bottom
Ash” by Rainer Bunge. (Click here to
download the report.)
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