Považská cementáreň, a.s. Ladce and sustainable development

The strategic mission of Považská cementáreň, a.s., Ladce is the environmental efficiency – production of the largest possible amount of cement with the highest utilization of alternative sources, the lowest formation of pollutants per ton of cement, the highest quality with the longest service life of buildings. Sustainable development is a part of the integrated policy of the company.

 1.       Introduction

The growing population and the increasing standard of living of the population increase the consumption of energy, products, water and at the same time increase the volume of waste, waste water and discharged emissions of industry, heating of buildings, passenger and freight transport. These requirements are met by industry and services.

Industrial production, such as cement, iron, aluminium, glass, paper production, etc., consumes a significant quantity of raw materials and energy. Gas, oil and coal deposits are shrinking and moreover, Slovakia does not have them. The ecological requirements for industry in the EU are demanding, requiring costly investments and, again, higher energy consumption. The impact of human activity on global warming due to the impact of carbon dioxide greenhouse gases poses a significant risk. Reduction of emissions and regulation of companies by EU CO₂ quotas since 2005, including the cement industry, threatens their competitiveness, future and thus social stability in a global perspective.

Považská cementáreň, a.s. Ladce (PCLA) was given the gift of limestone and marlite of Butkov by nature thanks to the wisdom of its founder. Other raw materials and energy must be imported. For already 130 years it has been producing the most important building material cement and in the last two decades also concrete. Concrete is currently the most important construction material. Concrete is the second most used material in the world after water, which we are currently unable to replace with an equivalent material. Since the main component of concrete is cement, which is an energy-intensive product, all cement producers strive to produce it efficiently, minimising its environmental impact.

 2.       How is cement made?

The basic raw materials are limestone and marlite from the Butkov quarry, which, after grinding with the necessary additives, are ground into a fine meal and dispensed into the rotary kiln system in a controlled manner, and at a temperature of 1400 °C Portland clinker is formed, it is then ground with additives - gypsum, limestone, blast furnace slag, fly ash and others, and the resulting product is cement.

This brief description shows possible environmental impacts on the surrounding area. It is mainly the formation of dust. Other major pollutants directly related to clinker firing are nitrogen oxides, carbon oxides, total organic carbon, ammonia and sulphur dioxide. All places with the possibility of dust escape are equipped with dedusting devices. There is a total of 73 of these in PCLA.

The Act on Air Protection allows the discharge of max. 10 or 20 mg of dust per cubic metre of air discharged from filters. The average amount discharged from PCLA dedusting facilities is below half of the prescribed limit. An important step of PCLA to prevent increased dust in the plant and its immediate vicinity was the commissioning of a closed circular clinker dump in 2017, which drastically reduced the amount of dust generated in the cement production.

The secondary source of dust is the storage of substrates such as slag, limestone, marl, or other additives. These are stored in an open and covered dump, in windy weather, dust escapes outside the dump, these are reduced by natural moisture.

3.       Investments in environment

In the last decade (2010 to 2019), PCLA investments directed to projects aimed at environmental protection amounted to more than 35.6 million EUR. These investments were made at various stages of the modernization of the plant, from the quarry to cement mill, or shipping of cement. The following figure shows the investments for the period under review.

The total cost of investments in the modernisation of the enterprise reached more than EUR 83.8 million in the period under review. Of these investments, over 42.5% were invested in environmental projects.

The amount of dust produced in the last decade, or the visible radical decrease in the amount of dust released by the operation of the closed clinker dump in 2017, is shown in Chart 2.

It should also be noted that in the framework of the implementation of all modernisation projects, dedusting equipment meeting the requirements for environmental quality were installed on technological units. However, the requirements are increasing, so PCLA systematically replaces dedusting equipment to meet the strictest limits.

The need to continuously adapt to the new environmental requirements to increase the environmental protection while complying with the BAT references (best available technique) led in 2014

to building a new technology for the reduction of nitrogen oxides in the flue gas of the rotary kiln by spraying a liquid solution of ammonia. Currently the maximum permitted value of concentration is 500 mg of nitrogen oxides (in the case of combustion of fuels other than fossil fuels only), expressed as nitrogen dioxide in one cubic metre of flue gas. Average annual concentrations of nitrogen oxides for each year are shown in Chart 3.

The installed BAT technology leads, on the one hand, to a reduction in emissions of nitrogen oxides, but, on the other hand, to an increase in the number of pollutants discharged by gaseous ammonia, given that no chemical reaction takes place with a 100% conversion. From the chemical point of view, we cannot consider the reduction of NOx by ammonia water, despite the state of the technology, to be effective. The maximum permitted concentration of ammonia discharged is 30mg in one standard cubic meter of flue gas. Average annual concentrations of ammonia for each year are shown in Chart 4.

 With a more detailed comparison of the pictures in 2015 and 2013 showing the average annual concentration of nitrogen oxides and ammonia, it is possible to compare the impact of the legislative change in the maximum permitted concentration of nitrogen oxides from 800mg/Nm3 to 500mg/Nm3 (2016) on the average annual concentration of ammonia in those years. In 2015, the average annual concentration of nitrogen oxides was 516mg/Nm3, compared to 432mg/Nm3 in 2016, but the average annual concentration of ammonia increased from 5mg/Nm3 (2015) to 15mg/Nm3 in 2016.

4.       Climate changes and the circular economy

Climate changes and energy consumption are the most important environmental issues for the joint stock company PCLA. The PCLA strategy for reducing CO₂ emissions is based on reducing the clinker content in cement, increasing the energy efficiency of clinker firing, using alternative fuels with high biomass content (renewable energy source) while reducing fossil fuels. Many factors limit the applicability of the different elements of this strategy.

Chart 5 shows the evolution of CO₂ emissions over the period from 2010 to 2019 in PCLA. Behind the decreasing trend lies the modernization of the rotary kiln line equipment and the associated higher energy efficiency of clinker firing, or the possibility of higher substitution of fossil fuels with alternative ones, as well as the actual use of several types of alternative fuels and alternative raw materials.

5.       Alternative fuels

The firing of clinker from raw materials is predominantly an endothermic chemical reaction, while approximately 60% of the heat needs to be supplied only for the decomposition of limestone into CaO and CO₂. The processes of combustion of fossil fuel such as coal or natural gas may be the sources of this heat.

However, at present, in the period of climate changes, the combustion of fossil fuels alone would be unsustainable, both in economic terms, in terms of their exhaustible reserves, as well as in terms of the amount of CO₂ emissions emitted.

Therefore, in clinker production, it was necessary to start with saving a part of fossil fuels (non-renewable naturally) and replace them with energy recovery of alternative fuels.

Považská cementáreň, a.s. Ladce shows an example of social responsibility for sustainable development. The rational need to reduce fossil fuel consumption and production costs is balanced with environmental benefits in the form of lower overall CO₂ emissions, better waste management and fewer dumps. In addition, under the European Commission Directive (Commission Implementing Decision establishing BAT conclusions under Directive 2010/75/EU of the European Parliament and of the Council), plants that co-incinerate alternative fuels, such as PCLA, must comply with stricter emission limits.

In short, why is it that co-incineration of alternative fuels (co-processing is probably a better expression) requires stricter emission limits than burning coal which is being abandoned? The limits for the individual pollutants (PM) as well as the measured average annual pollutant concentration values for 2019 are given in the table below.

Pollutant	Emission limit [mg/Nm3]	Average annual concentration of pollutant [mg/Nm3]
Particulates (PM)	20	8.9
Sulphur oxides expressed as SO2	50	4.0
Nitrogen oxides expressed as NO2	500	432.9
Total organic carbon (TOC)	50*	15.1
All gaseous chlorine compounds expressed as HCl	10	0.3
All gaseous fluorine compounds expressed as HF	1	0.1
Cd + Tl	0.05	0.005
Hg	0.05	0.02
Sb, As, Pb, Cr, Co, Cu, Mn, Ni, V	0.5	0.01
Dioxins and furans - PCDD and PCDF	0.01 ng/Nm3	5.0E-3 ng/Nm3
CO	-	1025.5
NH3	30	9.8

Note: *The emission limit for TOC has been determined individually because TOC does not come from waste incineration but from a raw material source

PCLA helps the society not only in waste management, but also places lesser burden on its surroundings. When co-incinerating alternative fuels, it is governed not only by the current legislation, but beyond it, it develops new patent technologies in PCLA.

As early as in 1983, PCLA was the first in Europe to start co-incinerating end-of-life tyres, with more than 119 thousand tonnes recovered by the end of 2019. This eco-innovation on the rotary kiln line built at the time of socialism continues to influence by positive aspects the protection of the environment in the form of reducing the potential of creation of dumps with end-of life tyres and at the same time reusing the material from which they are made, and this is an illustration of the circular economy.

A significant breakthrough innovation since 2001 was the start of the co-incineration of animal biomass, meat-and-bone meal (MBM) and animal fat (AF), by the end of 2019 PCLA used about 500,000 tonnes of MBM in material-energy recovery. By implementing this BITORIX innovation, PCLA helped the Slovak Republic to join the European Union in the chapter of agriculture, i. e. in the fight against mad cow disease, the so-called BSE, given that it was one of the conditions for entry.

Another major innovation was the co-incineration of the solid alternative fuel, the so-called SAF produced

from sorted wastes, in the rotary kiln line. Solid alternative fuels meet the requirements of the European standards STN N 15357 and 15359. The great advantage of its combustion in the rotary kiln of the cement plant over other methods of disposal is mainly:

• high temperature – up to 2000°C and a sufficiently long residence time at high temperatures to burn all organic substances,
• creation of a strong bond of residual ash to the cement clinker, binding of acidic components of flue gases in the alkaline furnace environment,
• bonding of heavy metals to cement clinker
• and their minimum leachability from concrete,
• high biomass content (renewable energy source),
• In 2010-2019, PCLA obtained 46.2% of the thermal energy required for clinker production by recovering alternative fuels. This has reduced the consumption of hard coal by extraordinary 370 thousand tonnes. In Austria or the Czech Republic, the share of fossil fuel substitution in cement plants is as high as 65 to 80%. The cement industry of the Slovak Republic cannot follow assumptions, but integrated permits, state of the technology and compete on the EU market. Chart 6 shows the percentage development of fossil fuels substitution by alternative fuels over the reference period 2010-2019.

6.       Environmental impact of alternative fuels

The risk from co-incineration of alternative fuels is assessed on a number of occasions, in particular the anticipated environmental and human health impacts. It is also considered that waste has a high content of heavy metals. For comparison, the table below describes the content of some metals in different materials in mg/kg, i.e. millionths of a kilogram.

Metal	SAF	Limestone	Hard coal	Soil
As Cd Cu Cr Co Hg Mn Pb Tl Zn Ni	0.86 4.4 105 85 3.3 0.3 44 97 <0.5 410 15.5	0.2-70 0.03-3 - 20-180 - 0.05-0.6 - 0.8-27 0.05-0.8 1-200 1.5-16	0.2-0.4 1.4 110-450 2-6 43-88 0.05-0.6 120-360 0.7-1.5 2.6-4.9 20-150 1-37	40 2 - 200 - 10 - 500 2 300 100

The overviews show that, compared to the co-incineration of alternative fuels, ordinary soil exceeds the heavy metal content several times. At the same time, it should be emphasized that most of heavy metals are firmly bound in clinker minerals, thus their effect is practically minimized.

In the production of cement, the most important raw material is clinker (semi-finished product), which is produced by firing of the fine, so-called furnace meal in the rotary kiln, and of two basic raw materials - limestone and marl. The figure below shows that the largest source of CO₂, about 60% in the clinker production, comes from the thermal decomposition of limestone, which cannot be technologically influenced. The second largest source is the combustion of fossil fuel – coal, with the degree of its replacement with alternative fuels of about 54% (year 2019). Chart 7 also shows that during the co-incineration of meat-and-bone meal, which is 100% MBM (renewable energy or carbon passes from one form to another with constant repeatability of this cycle), theoretically no CO₂ emissions are released. The same applies to the co-incineration of solid alternative fuels made from sorted industrial waste and they also contain a high proportion of biomass at the level of approx. 40%.

Therefore, Považská cementáreň plant aims at continuous modernization of the rotary kiln line and implementation of innovation to achieve the share of alternative energy at the level of 80%, which would again reduce the amount of CO₂ discharged and also reduce the burden on the environment by dumps of waste that can be energy recovered.

For comparison, the next chart shows the percentage of CO₂ emissions from limestone decomposition

and the combustion of fossil fuel with its replacement with 80% alternative fuels, the amount of clinker produced being the same as in the previous case.

From the increase in the share of alternative fuels to 80%, it is clear that the total amount of CO₂ emissions emitted decreased by 24 thousand tonnes. The second largest source of CO₂ emissions is the combustion of solid alternative fuel, while the percentage of emissions from the decomposition of limestone (furnace meal) increased by 5%, but in absolute values it remained the same, due to the same amount of clinker produced, or the same amount of limestone.

By co-incineration of alternative fuels for the period 2010-2019, Považská cementáreň plant released by extraordinary 685 thousand tons of CO₂ less into the air than it would have emitted in the combustion of only the standard fossil fuel coal, the availability of which is decreasing. The following table shows the amounts of CO₂ emissions released when burning different types of fuels needed to produce 1GJ of heat, i.e. an increase of the share of fossil fuel combustion increases the greenhouse effect.

 

Table No. 3: Quantity of fuel and released CO₂ emissions necessary for the production of 1 GJ of heat

Fuel	Fuel quantity [kg]	Quantity of CO2 emissions [kg]
Hard coal	34.2	97.1
Natural gas	28.6 Nm3	55.7
MBM	58.4	0
SAF	41.9	52.1
Tyres	38.1	17.1

The current waste management legislation in force states that the incineration of solid alternative fuel, produced from sorted industrial waste, is only energy recovery and cannot be characterised as waste recycling. That statement is questionable, whether on the basis of the material balance of the input and output of currents from the rotary kiln line or from the laboratory tests actually carried out in the company PCLA. It does not take into account the material balance, or the law of preserving solid alternative fuel, ash will be generated at the level of 15% of the fuel weight and this ash is firmly bound to the clinker structure. Co-incineration of alternative fuels in a cement kiln is therefore a waste-free technology (which other technology is waste-free?), which not only energy but also materially recovers waste, i.e. also recycles it, which is a typical example of a circular economy.

In the period 2010-2019, the co-incineration of alternative fuels MBM, tyres and solid alternative fuel (SAF) in the rotary kiln line generated ash in the amount of 98 thousand tons, which became a part of the clinker produced, i.e. for the production of this clinker, without the use of ash, we would need by 163 thousand tonnes of limestone more, which we saved for the next period, and additionally 523 thousand tonnes of waste would remain in dumps as our legacy to future generations.

7.       Monitoring, reporting and communication

PCLA pays great attention to the environment

-          integrated management system

-          risk management and environmental targets

-          integrated management system evaluation report

-          independent audit according to EN ISO 14001:2015

-          inspection of environmental authorities

-          update of the integrated permit

-          continuous emission monitoring system

-          communication with municipalities in the vicinity

-          selfless assistance to the state administration/customs offices

-          maintenance of green spaces and noise reduction

-          cleaning of roads outside PCLA, where fallen dust is formed not only by PCLA, but also by traffic and surrounding companies

-          reporting to the Ministry of the Environment, Slovak Environment Inspection, District Environmental Office, Slovak Hydrometeorological Institute, Slovak Water Management Enterprise, municipal office, administrator of emission allowances ICZ

-          suggestions of the Slovak Environment Inspection, District Environmental Office, municipal office

-          eco-design and quality of cements with a lower carbon footprint

-          development and application of technologies reducing CO₂ emissions

-          PCLA site waste sorting

-          etc. …

As you can see, the coverage of environment in PCLA is enormous.