Lignite fly ash

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Lignite fly ash is an industrial by-product that is obtained as fly ash when dry lignite is burned in power plants . It is used in road construction and earthworks for soil improvement, as well as a substitute for binding agents and as an additive in concrete .

Due to the different composition of the burned lignite and the different firing conditions, the lignite fly ash fluctuates considerably in its composition.

composition

This paragraph shows the situation in Germany . Help us to describe the situation in other countries.

Main components in percent

substance Rhineland Central Germany Lausitz
SiO 2 20-80 15-45 32-68
Al 2 O 3 1-15 7-23 5-14
Fe 2 O 3 1.5-20 1-11 6-22
CaO 2-45 25-52 8-23
CaO free 2-25 5-25 0.1-4
MgO 0.5-11 2-6 2-8
K 2 O 0.1-1.5 0.1-0.5 0.5-2
Na 2 O 0.1-2 0.01-0.2 0.01-0.2
SO 3 1.5-15 3-15 1-6
TiO 2 0.1-1 0.5-1.3 0.2-1
Cl <0.2 <0.1 <0.02
C. <2 <1 <2

Trace elements in mg / kg

element Rhineland Central Germany Lausitz
As 10-43 10-40 0.5-30
Pb 5-80 10-50 2.5-30
CD 0.2-2.1 <2 0.1-1
Cr 18-70 10-60 10-70
Cu 10-175 5-35 2-30
Ni 8-50 5-40 3-65
Ed <1 <1 <1
Zn 30-150 10-80 5-65

Physical Properties

The bulk density of lignite fly ash is usually between 2.4 g / cm³ and 3.3 g / cm³. The bulk density is usually between 0.7 and 1.5 g / cm³. The Proctor density usually varies in the range from 1.1 to 2.0 g / cm³.

Problems

Before the introduction of modern filter technology in lignite power stations and during the times of large-scale lignite briquette production, a large part of the lignite fly ash was released directly into the environment and deposited on the agricultural land in the area. Due to this increase in the carbon content of the soils, these were for a long time to be regarded as particularly "problematic" when using herbicides in sugar beet cultivation , since the active ingredients of the agents were partially determined by the carbon (see also: activated carbon ).

Individual evidence

  1. ↑ Leaflet on the use of power plant by-products in road construction - M KNP - Edition 2009