6 Overall assessment, Danish Environmental Protection Agency

Mass Flow Analysis of Chromium and Chromium Compounds

6 Overall assessment

6.1	Chromium consumption in Denmark, 1999
6.1.1	Net import of chromium and chromium compounds
6.1.2	Consumption of chromium and chromium compounds
6.2	Chromium input to the environment and landfills
6.2.1	Emissions to air
6.2.2	Emissions to water
6.2.3	Emissions to soil
6.2.4	Landfills
6.3	Chromium balance for Denmark, 1998–2000

6.1 Chromium consumption in Denmark, 1999

6.1.1 Net import of chromium and chromium compounds

Chromium and chromium compounds are imported with goods, raw materials and semi-finished goods (metals) as a chemical substance and as a trace constituent. The net import of chromium as a trace constituent/alloy metal in stainless steel, ferrous chromium, steel and iron has been calculated to be 23,200–28,500 tonnes. The net import of chromium as a trace constituent/alloy metal in aluminium and copper is 11–106 tonnes and 6–9 tonnes, respectively.

Chromium compounds are primarily imported in the form of chromium oxides, but also in the form of chromium hydroxides, chromium(III) sulphate, sodium dichromate and other dichromates. The total quantity of imported chromium compounds has been calculated to be 260 tonnes, of which chromium(VI) accounts for approximately 110 tonnes.

In addition to this, chromium is also imported as a trace constituent/impurity in a number of products. The most significant of these are fossil fuels (coal and oil, accounting for 147 tonnes) and chromium leather (accounting for 79–209 tonnes chromium).

6.1.2 Consumption of chromium and chromium compounds

The consumption of chromium as an alloy metal, chemical compound and trace constituent has been identified for Denmark for the year 1999 (average for the years 1998, 1999 and 2000). Table 6.1 provides an overview of this consumption.

Table 6.1
Consumption of chromium, chromium compounds and chromium as a trace constituent in Denmark in 1999 (average for the years 1998, 1999 and 2000).

	Supply (tonnes/year)	Share of total (%)
Chromium, metallic	24,300–29,400	97
Chromium compounds	450–740	2.2
Chromium as a trace constituent	214	0.8
Total	24,964–30,354	100

Table 6.2 provides an overview of the consumption of chromium and chromium compounds in Denmark by area of application.

In the effort to establish an overview of the consumption of chromium compounds, emphasis has been placed on identifying consumption and emission of chromium(VI) compounds. These compounds constitutes a significantly greater risk to health and the environment, as described in section 1.34, "Classification of chromium compounds". Use of chromium(VI) compounds is subject to a wide range of restrictions. As a result, consumption of such compounds is falling within many areas.

Table 6.2
Consumption of chromium, chromium compounds and chromium as a trace constituent in Denmark in 1999 (average for the years 1998, 1999 and 2000), by area of application. Consumption of Cr(VI) is also stated for the relevant applications.

Area of application	Consumption (tonnes/year)	Share of total¹ (%)	Of which Cr(VI) (tonnes/year)	Development trend
Chromium, metallic – Iron and steel – goods, iron and steel – goods, other steel – steel production – Aluminium alloys² – Copper alloys²	21,000–25,000 2,700–3,700 600 11–106 6–9	83 12 2.2 0.2 0.03	– – – – –	rising rising rising rising rising
Chromium compounds – Surface treatment – Pigments in paint and – plastic – Impregnation – Corrosion inhibitor – Tanning – Catalysts – Hardeners – Textiles – Electronic storage – Laboratory chemicals – Firebricks	37.7 12.6–116.7 8.8 ~0 164–302 0.1–1 13–47 5.6–16.7 1.8–2.6 <1 200	0.14 0.23 0.03 0 0.8 0.002 0.11 0.04 0.008 0 0.72	37.7 1–2 8.8 – 0.016–0.035 – <<1 – – <1 –	rising falling falling – rising ? ? no change no change – no change
Chromium as a trace constituent – Coal and oil – Cement	147 67	0.53 0.24	– 2.1–4.2	no change falling
Total	24,964–30,354	100.28	49.6–52.7


¹	The sum deviates from 100% due to rounded-off figures.
²	Including impurities in aluminium and copper.

6.2 Chromium input to the environment and landfills

Table 6.3 provides a summary of the information available about disposal and dispersion of chromium to the environment in Denmark in 1999. Emissions to various recipients are discussed below.

6.2.1 Emissions to air

Chromium and chromium compounds are stable compounds with high melting points/boiling points. This means that emissions to air are primarily associated with thermal processes. Thermal processes mainly occur in connection with production and processing of iron, aluminium and copper, including alloys of the various metals. No primary production of such metals or alloys takes place in Denmark, but processing may occur. Similarly, recycling of metals also takes place in Denmark. The most significant sources are incineration (energy conversion and waste incineration) and processing, use, recycling and disposal of iron, steel, aluminium and copper. The total emissions to air have been calculated to be 4.1–5.5 tonnes Cr/year.

6.2.2 Emissions to water

Chromium and chromium(III) compounds are relatively insoluble in water. Some chromium(VI) compounds, however, are more soluble, which means that emissions to water may occur, e.g. in the form of discharges of process chemicals from surface treatment or wastewater from the paint/varnish industry. During the use phase, emissions to water will primarily occur in connection with the following: corrosion of iron, steel, aluminium and copper; use of paint that contains chromium pigments; leaching from impregnated wood, or disposal of laboratory chemicals. The total emissions to water can be calculated to be 1.9–4.0 tonnes Cr/year.

6.2.3 Emissions to soil

The conditions for solubility of chromium compounds described above also apply in connection with emissions to soil. This is to say that emissions during the use phase will primarily occur in connection with corrosion of iron, steel, aluminium and copper, leaching from impregnated wood and painted surfaces, and peeling from chromium plated products. The total emissions to soil are in the range of 16–33 tonnes Cr/year.

6.2.4 Landfills

Chromium and chromium compounds enter landfills as part of various products and in residual products from incineration processes. In addition to this, small quantities will enter landfills as part of building waste, leather and textiles. The total chromium input to landfills is in the range of 148–244 tonnes/year.

Table 6.3
Chromium disposal and dispersion to the environment in Denmark,1999.

Process/source	Air tonnes/ year	Water tonnes/ year	Soil tonnes/ year	Landfill tonnes/ year	Total tonnes/ year
Industrial processes – Processing, use and disposal – of iron and steel – Recycling of iron and steel – Processing, use and disposal – of aluminium – Processing, use and disposal – of copper – Energy conversion (coal and – oil) – Other industrial processes – Surface treatment – Tanning – Transport	? 0.1–0.2 0–0.1 ~0 3.5 – – – – 0.2	? 0.017–0.034 0.2–2 – – 0.2 0.089 ? 0.27 –	15.5–31 – 0.1–1 0.1–0.2 – – – – – –	– 2.3 3–37 1–2 ? – – – – –	15.5–31 2.4–2.5 3.3–40 1.1–2.2 3.5 0.2 – ? 0.27 0.2
Use of products – Impregnated wood – Chromium-plated products – Paint – Laboratory chemicals	– – – –	0.3–0.6 – 0.03–13 <<1	0.3–0.6 ?? – –	– – – –	0.6–1.2 ?? 0.03–13 <<1
Waste treatment – Waste incineration – Biological waste treatment – Landfilling of solid waste – Kommunekemi – Municipal wastewater – Wastewater sludge	0.3–1.5 – – ? – –	– – – – 1.2 –	– 0.086 – – – 2.1	36–96 – ?? 104–107 – 1.4	36–98 0.086 ?? 104–107 1.2 3.5
Total	4.1–5.5	2.3–17	16–33	148–244	170–302

6.3 Chromium balance for Denmark, 1998–2000

The chromium balance for Denmark for the period 1998–2000 has been established on the basis of the information and data presented in sections 2–5 of this document. See Figure 6.1. This figure illustrates the quantities imported into and exported from Denmark, as well as the emissions to landfills, air, soil and water. Denmark is represented by the central box in the figure. This box lists the various uses of chromium. Collectively, these uses constitute the total consumption in Denmark. A certain percentage is re-circulated internally in Denmark. The accumulation within Danish society constitutes an expression of the balance between the chromium input to society and the chromium leaving the country through export and emissions.

The balance comprises:

Net import with metals and chemical compounds and as a trace constituent

Net export with scrap metal

Emissions to air, soil and water

Metallic chromium includes chromium found in alloys or as a trace constituent in aluminium and copper.

Figure 6.1
Chromium balance for Denmark 1999 (tonnes Cr/year, average of the years 1998, 1999 and 2000).

On the basis of the calculated net import, net export and landfilling, the accumulation is estimated to be around 0. Metals containing chromium (iron, aluminium and copper) are valuable within the recycling system. As a result, such metals will be sent for recycling. This does not, however, entirely rule out the possibility of accumulation.