TECHNICAL FIELD OF THE INVENTION The present invention generally regards earth construction material and a process for manufacturing earth construction material from recycling waste. More in particular, the present invention regards the manufacture of material fit for earth construction from screening fines and even more in particular using heat treatment.

BACKGROUND OF THE INVENTION

It is, as such, consistent with prior art to use, for example, aggregates as a raw material in the asphalt process. In this case, it is however often necessary to use gravel, which is taken from the ground, from a gravel extraction site, which is detrimental to nature and especially scenic aspects. Gravel can also be produced through crushing, in which case the aggregate can be obtained from rock or from some other similar aggregate. In this case, crushing the rock, as such, produces dust and noise and also requires energy for using crushers. Usually materials suitable for asphalt require a certain coarseness, whereby larger-grained fractions are screened for crushing and the finer ones are removed from among the applicable fraction.

In the process to make asphalt, as such, also tar-like pitch substances are used to bind the aggregates at an elevated temperature into an asphalt coating, which is spread on a road’s surface. In this case, the pitch used in manufacturing asphalt, in a melted form or softened to almost such a form, binds the aggregate to the asphalt structure when the pitch is allowed to cool on the road’s surface.

Also known are treatment processes for contaminated soil, in which the soil is heated at a sufficiently high temperature so that the evaporating substances are removed from the soil being processed. However, in treatment taking place at a temperature below 300 °C, thermodesorption, volatiles do not yet significantly decompose.

In the treatment process for contaminated soil, the thermic treatment thermodesorption (400-700 °C) for the removal of volatile substances from the soil is usually carried out at a fairly low temperature, after which any gaseous compounds released in it can be, as applicable, combusted or scrubbed to be separate from the composition’s other components, whereby the details of the treatment depend on the composition of the original pollutant.

Depending on the degree of purity, the treated soil can, as applicable, be used, for example, for making asphalt if it would otherwise, as such, be applicable even partially as a raw material in the asphalt process or it can be returned to where it was originally taken from for decontamination.

It is possible, however, that the contaminated soil might still, after the treatment of the soil, have residues of difficult-to-evaporate pollutants/other hazardous substances, perhaps even of materials resulting from the process, which would, in groundwater areas, be flushed into the groundwater when the surface runoff is absorbed through the water permeable soil layers over decades.

SUMMARY OF THE INVENTION The purpose of the present invention is to alleviate the above-mentioned problems which are also connected to enabling the use of previously unused screening fines considered to be waste material in recycling as a raw material for earth construction material manufactured using it.

When screening fines material is formed by screening in order to separate different screened fractions from one another, the last fraction, screening fines, is fairly fine but often also a heterogenic substance, whose composition may, as such, vary depending on the source of the screening fines, in other words, depending on from which source the screening fines material is originally from, how the material found in it has been crushed as such and what material batches of materials sourced from different screening fines sources have been combined in the batch that ends up at an individual screen and from which the screening fines are formed by screening for use as a reactant in the process according to an embodiment of the invention.

The purpose of the invention is achieved with a process according to an aspect, wherein the reactor plant to be used is formed by a sintering plant according to an independent claim concerning it, which sintering plant is arranged for the heat treatment of the screening fines in order to form the earth construction material. The sintering plant according to the invention uses a method according to the invention to form the earth construction material.

The method according to the invention for forming earth construction material is characterised in what has been presented in the characteristics section of the independent claim 1.

Preferred embodiments of the invention are also presented in dependent claims.

According to an aspect of the invention, the method according to the present invention for forming earth construction material from screening fines material by sintering, comprises stages, wherein screening fines are fed into a sintering drum functioning as a reaction vessel,

the screening fines fed into the reaction vessel are warmed/heated in it in order to sinter the sinterable matter of the composition,

the reaction vessel is rotated at least around an axis,

the sintered material suitable for earth construction is removed from the reaction vessel as earth construction material,

the earth construction material is cooled.

According to an embodiment of the invention, sintering of the screening fines means the sintering of the screening fines’ sinterable material fraction. In this case, the combustible components of the screening fines material are combusted, as applicable, in the sintering drum.

According to an embodiment of the invention, the warming/heating is continued up to the sintering temperature of the structural units of the screening fines material in order to form material suitable for earth construction as a result of heating.

According to an embodiment of the invention, the warming/heating is based, at least in part, on combustion, on the combustion of the combustible matter accompanying the screening fines in the presence in the reaction vessel of the air/oxygen fed into the reaction vessel. Thereby, the sinterable portion of the screening fines material remains for sintering. According to an embodiment of the invention, the warming/heating is based, at least partly, on the cooling residual heat recovered using heat exchangers, which is directed to the start of the reaction vessel.

According to an embodiment of the invention, in addition to the screening fines, fuel is fed into the reaction vessel in order to achieve and/or maintain the sintering temperature for the screening fines fraction, from which is formed the earth construction material.

According to an embodiment of the invention, in the process at least one predetermined tracer is added to the reaction vessel, which has a process-specific composition for the process used by the manufacturer in order to identify the manufacturer and/or its material.

According to an embodiment of the invention, after sintering the earth construction material suitable for earth construction is conducted out of the reaction vessel into a cooling space. Heat can be recovered from the cooling space using heat exchangers in order to warm the reaction vessel and/or screening fine feed.

The earth construction material according to the invention has been manufactured using a method according to an embodiment of the invention.

In the reactor plant according to the invention for the forming of earth construction material from screening fines material by sintering, the reactor plant comprises

- a feeder for feeding the screening fines material to the sintering drum arranged to act as a reaction vessel,

- a sintering drum for sintering at least a screening fines material fraction,

- an end material cooler in a heat exchange arrangement for recovering and using heat for warming/prewarming the substance reacting in the reactor,

- an afterburner for burning in post-combustion the material released from the sintering drum and/or that remains unburnt in it,

- a cooling unit in the heat exchange arrangement following post combustion for recovering heat from the post-combustion flue gases, and/or for using for warming/prewarming the substance reacting in the reactor,

- a dust removal unit for removing dust from the post-combustion flue gases, - a flue gas scrubber for altering the composition of the flue gases,

- A flue gas duct for the removal of flue gases from the reactor plant.

According to an embodiment of the invention, there is a supply line to the sintering dmm for the feeding of additional fuel to the sintering drum according to a combustion stage of staged combustion in sintering.

According to an embodiment of the invention, the combustion air supply in the reactor plant has been arranged to corresponds with each stage of the staged combustion into the sintering drum.

According to an embodiment of the invention, the reactor plant has a feed of a predetermined tracer into the sintering drum at the end stage of the sintering and/or in connection with the cooling of the end material.

According to an embodiment of the invention, in the reactor plant there is arranged for the dust removal unit an additive feed for the altering of the electrical/chemical composition of the surface layer of the dust/fly ash for increasing the effectiveness of the removal and/or for altering the dust sintering characteristics in the reaction vessel.

According to an embodiment of the invention, the sintering drum has been arranged to rotate at a specific rotation speed (which, according to an embodiment, can be controlled through a control centre) in relation to a rotational axis. According to an embodiment, the rotational axis is tilted such that the tilt angle of the rotational axis can be adjusted, under the control centre. Thus, by adjusting the tilt angle, the residence time of the sintering material in the sintering dmm can be impacted and thus the process itself can be adjusted for optimising the functionality of the method to best suit the composition of a specific screening fine.

According to an embodiment of the invention, the reactor plant has a feedback channel for the dust removed with the dust removal unit to the sintering dmm for using the dust as a raw material alongside the screening fines.

The utility of the method according to the invention and the material manufactured using it is based on numerous factors. In this case, waste material can be recovered through recycling, when refined as a material that can be formed in an industrial-scale facility in which material formed from screening fines is processed by sintering screening fines material.

In a process of a plant according to an embodiment of the invention, earth construction material is formed such that the screening fines are loaded, as applicable, for example with a wheel loader onto a feeder, for example into a silo, whereby the substances to be fed can be divided according to suitable fractions, for example into one or two different compartments, whereby the fractions can be dosed as applicable in the process and possibly used in the steering of the process by controlling the feed of different fractions. In this case, the volume of the fed material could be adjusted in the feeder, even using a specific type of feedback, based on the properties or measured variables detected in the end material, for the dosing of the reactants in suitable ratios. Controlling can take place through a control centre, in which the process-specific data gained from the measurement sensors is collected and used, as applicable, in the controlling of the process actuators for adjusting the material properties.

A feeding conveyor can be used to move material from the feeder to the sintering drum. The feeding conveyor can have a scale, as such, with which to measure the amount of fed material.

Screening fines material is sintered in a sintering drum at the sintering temperature, which can be between 600-1,400 °C according to an embodiment. According to a second embodiment variant, the sintering temperature is 1,000-1,450 °C, according to yet a third embodiment variant the sintering temperature is 1,100-1,300 °C. According to an embodiment variant, sintering is carried out according to a varying temperature profile in accordance with the sintering drum’s parts at different temperatures in accordance with the location of the reactant moving forward in the process.

According to an embodiment of the invention, as such, the entire screening fines material as is, is not sintered; instead the sinterable components it contains are sintered from it (especially for example glass wool and/or glass) are sintered and achieve, in addition to the combustible components (for example plastic, wood), a condensing sinterable structure. However, the aggregate contained in the screening fines will not necessarily, as such, become sintered, in which case the entire screening fines material as such is not sintered. In this case, it is obvious to those skilled in the art, when sintering the screening fines based on the embodiments of the invention, a non-combustible portion of the screening fines material that is fed into the sintering dmm takes part in the sintering, which does not burn, as such. With the help of the combustible portion, heat can be brought to the sintering drum, and its interior parts, including the sinterable fraction, can be heated.

For example, biogas or alternatively fuel oil can be used as a support fuel. Support fuel can be fed from several parts of the sintering drum, whereby the feeding can be staged if necessary and also the combustion can be controlled by adjusting the stage- specific oxygen partial pressure. The oxygen can be the air’s oxygen. Feeding of the support fuel and the air supply required to burn it and the staging of their feeds can be arranged based on the measurements of the control centre measurement sensors. In this case, an opacity meter, for example, can be used in the removal of flue gases to determine the concentration of the particulate material and thereby increase or even reduce the removal of the particulate matter from the process in connection with the post-combustion. The sintered material is removed from the sintering drum, for example, using a discharge conveyor, in which the material can be cooled. The material could also be left to cool and/or be packed in a suitable manner if the degree of cooling allows it in a material form that is suitable with regard to the end material.

Combustion gases released in the sintering dmm can be conducted into the afterburner. When processing the combustion gases in the afterburner at a temperature of at least 850 °C, for example with a residence time of two seconds, the combustible substance can be burned and the correct temperature can be ensured with a suitable gas/oil burner.

From the afterburner, the combustion gases are conveyed in the process to coolers in which the temperature is lowered to approx. 180 °C. The cooler can be arranged to be a heat exchanger according to an embodiment, whereby the resulting waste heat can be taken from the cooler for re-use, as applicable, in the process itself or elsewhere, for example, in the warming of the plant carrying out the processing of the screening fines material and/or the warming of the district heating network’s carrier substance.

Cooled combustion gases can be conducted into a dust removal unit, whereby, in the process, the particle-like dust that has ended up in the process at its start in connection with feeding or formed from mineral-like matter in the process itself and/or fly ash formed in connection with the combustion can be removed, as applicable, from the gases and transferred for transport, for example, using a screw conveyor to the end stage of the sintering drum. If necessary, dust can also be conducted back into the sintering drum for use in the process as a raw material, so to speak, as applicable. The transport can be carried out like a conveyor belt or with conveyers but also transport in a gas flow can be used, whereby the partial pressure of oxygen is most preferably arranged to be so low that no risk of dust explosion results.

After the dust removal, the gaseous portion of the combustion gases is conducted, for example, with a suitable fan or similar vacuum/fan to the gas scrubber unit, in which oxides of sulphur, chloride and nitrogen, for example, are scrubbed from the combustion gases into a water-soluble form and the gases are conducted into a stack. At the same time, nitrogen and sulphur oxides formed in the combustion and/or otherwise released from the reactants can be removed. In the smoke stack continuous multi-gas metering can be used to monitor and control emissions, to control the process under the control centre and, for example, an opacity meter can also be used for observing the proportion of particulate material in any emissions, and in order to start up counter-measures, if the particle emissions were to appear to be increasing past a specific guideline limit.

The screening fines recycling waste often contains matter that either rearranges itself, reacts, as applicable, with the other components in the process or burns away, whereby the material fed in can change such that the end material received from the process only forms some 20% of the in- fed material’s bulk density. The volume of the end material can decline significantly but its weight loss can be in the vicinity of only 10-15%.

The end material created in the process can be utilised, for example, in earth construction as an earth construction material, whereby, for example, gravel and/or aggregates can be replaced by suitable material forms of the end material.

The temperatures used in the process according to an embodiment of the invention can be even up to approx. 1 ,400-1 ,500 °C, in which case the equipment and especially the sintering drum’s and afterburner’s heat resistance each require a structure and materials of which these parts must be manufactured to correspondingly withstand the high temperatures used by the process, even if the sintering temperatures were to vary in accordance with each screening fines batch fed into the process. This enables the utilisation of sintering in the forming of the end material’s material form, however, without significantly fusing the reactant components intended for sintering.

Fusing as such can be difficult in terms of the process, especially if the fed reactants form a composition, which when cooled quickly crystallises or otherwise forms a uniform solidified phase, which can spoil the reaction vessel. On one hand, the objective of sintering is to combine specific parts of the screening fines material, but on the other, a grainy form that can be handled and, if required, refined, without a risk of spoiling the equipment due to material that has fused and cooled in it.

In this application the term“amount” shall mean any positive whole number starting from one (1), e.g. one, two or three.

The term“set” shall refer to whole numbers starting from the number two (2).

Screening fines material refers to a material that is formed by screening and whose grain size is approx. 0-25 mm, after the lowest screen in the screening. In particular the REF screening fines and/or FLUFF screening fines are, as the objects of the embodiments of the invention, suitable raw materials for manufacturing earth construction material. REF screening fines may contain fractions originating in construction waste and/or the soil, without being solely restricted to the composition in accordance with what is mentioned. FLUFF screening fines can contain electronics, metal, plastic etc. other waste in a crushed form, without being solely restricted to the composition in accordance with what is mentioned, in the screening fines in a screened form according to the screening fines’ grain size. The REF screening fines and FLUFF screening fines are thereby formed from materials that are, in practice, landfill waste from crushing and screening processes that are known as such.

BRIEF DESCRIPTION OF THE FIGURES

The following is a detailed description of the invention’s preferred embodiments, referring to the attached figures, in which

Figure 1 is an exemplary illustration of a diagram, of a reactor plant according to an embodiment of the invention for manufacturing earth construction material, Figure 2 shows an example of earth construction material according to an embodiment of the invention

Figures 3 and 4 illustrate an example according to an embodiment of the invention of the process for manufacturing earth construction material, and

Figure 5 illustrates an example according to an embodiment of the invention of a control centre for controlling a process according to an embodiment of the invention.

MORE DETAILED DESCRIPTION OF THE FIGURES

Figure 1 illustrates a process according to an embodiment of the invention and at the same time of a reactor plant for manufacturing earth construction material from screening fines material. In the figure the reference number 1 illustrates the feeder, with which screening fines material can be received and fed into the process. Reference number 2 illustrates a feeding conveyor with which screening fines material can be transported to the sintering dmm 3 for processing. The feeding conveyor 2 can also comprise a scale or a similar weighing system for assessing the amount of screening fines material at the feeding end of the sintering drum.

The afterburner 4 is used to burn, according to an embodiment of the invention, the, as such, combustible components from the gaseous substance arriving from the sintering drum. This makes it possible to ensure that the compounds released from and/or formed from the screening fines material during sintering change into non- hazardous compounds in connection with combustion, and they can be removed later from the flue gases using the dust removal unit 7 and the flue gas scrubber 8 before the flue gases are conducted to the smoke stack 9.

Emissions can be monitored with emission measurements. Post-combustion can be staged as applicable, such that by feeding combustion air the partial pressure of oxygen can be made to correspond with the stoichiometry of the combustible material in order to achieve as complete a combustion as possible. The air supply of each stage can be connected under the control centre, with an actuator adjusting the air supply of the staging adjusting the feed according to, for example, the measurement result of the opacity meter and/or the concentration measurement result of the gas analyser. The amount of sulphur dioxide, sulphur trioxide, nitrogen oxides and carbon monoxide in the flue gas can be measured from the emissions using suitable gas analysers according to the embodiment variant, but also particulate matter, for example using an opacity meter. The emission measurement data can be used to control the process as feed data to the control unit as statistical data and/or in order to alter the process’s control parameters.

Reference number 6 illustrates a cooling unit with which the combustion gases coming from the afterburner from the flue gas duct 5 are cooled to a temperature of approx. 130-200 °C. In this case, particulate matter, especially mineral residues can act as condensation cores, enabling the growth of the particles through nucleation- condensation mechanisms.

The dust removal unit 7 can be a traditional electrostatic precipitator, whereby sulphur oxides can be used in collection of particulate matter by impacting the surface resistivity of the particles and thereby the functioning of the electrostatic precipitator. Alternately or in addition, also a bag filter and/or cyclone can be used, which can be utilizable in flue gas cleaning units in particle removal, as such consistent with prior art.

According to an embodiment of the invention, for example using a conveyor, the feeding of the removed dust can be conducted from the dust removal unit 7 back to the sintering drum 3 to be used there as a raw material in the process. In this case, the material collected can be conducted into the sintering drum during the cleaning cycle of the bag filter or similar filter-based solution.

Reference number 8 illustrates a flue gas scrubber consistent with prior art as such for scrubbing sulphur and/or nitrogen oxides from flue gases, as applicable. The flue gas scrubber can also, as applicable, consist of two or more parts for the scrubbing of a specific flue gas component from the flue gases before emission through the smoke stack 9 into the atmosphere. In connection with the smoke stack, an emission measurement can be carried out for determining the dust and/or gas concentrations and/or the non-combustible portion.

Reference number 10 illustrates a cooler with which the earth construction material is cooled or allowed to cool. In this case, the cooler can be used as a heat exchanger and the released heat can be recovered and it can be recycled back into a suitable part of the process, for example the start of the sintering drum 3 (on the feeding conveyor side), for the prewarming of the reactants. The released heat can also be used, as applicable, according to an embodiment variant, for the prewarming of additional fuel.

Similarly as the cooler 10, also the cooling unit 6 can be used for the recovery of heat from the flue gas cooling using a heat exchanger arrangement connected to it.

Reference number 1 1 illustrates the process end material before it is processed into a suitable material form.

Figure 2 illustrates the material form 201 of the earth construction material according to an embodiment of the invention as a grainy material. The material can be packed, for example, into intermediate bulk containers and used, for example, like gravel as a filler in earth construction where the material is applicable.

Figure 3 illustrates a reactor plant according to the process. Reference number 1.0 illustrates the loading of screening fines onto the feeder 1.1. The feeder can be fed according to an embodiment with the fines of different screening fines screens, in which case their particle/grain size can vary in the fraction screened in accordance with the screening fines.

Reference numbers Jl, J2...Jn illustrate different screening fines fractions and the feeding devices used in their feeding for the dosing of the feed through the actual feeder to the conveyor 1.2. The dosing of the fractions can be controlled through the control centre, which is illustrated using an arrow and a dotted line ring around the feed coupling. According to an embodiment of the invention, feeds J 1 , J2 and Jn can be arranged to be independent of one another. Jn illustrates an embodiment in which there can be more than two fractions.

In connection with the conveyor 1.2 there can be a scale with which the amount of feed travelling through the conveyor to the sintering dmm 1.3 can be weighed. According to an embodiment, the feed can also be monitored using a camera in whose image range the fed material is when passing the camera. In this case, the camera can be used to measure the darkness of the feed, for example, in addition to its visual impression, whereby, if required, the composition of the feed travelling along the conveyor can be changed before it ends up in the sintering drum 1.3 for sintering. According to an embodiment of the invention, additional fuel can also be fed into the sintering drum 1.3 through an additional fuel feed, which is illustrated using the dotted line arrow. A box and an arrow emerging from it illustrate the temperature adjustment in the sintering drum reactor temperature range 600-1,100 °C under the control centre, which is illustrated with a box‘control centre’ and the filled-in arrow emerging from it.

The letter X illustrates heat exchanger arrangements, which are used in the example to illustrate the prewarming of the additional fuel feed and the opportunity (dotted line) for the use of the warming for the warming of the fed screening fines material before the feed into the sintering drum 1.3 and/or after the feed.

The symbol S used for reasons pertaining to drawing technique illustrates the supply of heat from the afterburner’s flue gas cooling unit 3.2 to the heat exchanger arrangement X when the temperature of the flue gases is reduced using the cooling unit 3.2, for example, from approx. 1,100 °C to approx. 150 °C as the flue gas duct temperature.

The sintering drum 1.3 is illustrated as a reactor vessel in Figure 3. The sintering dmm has been arranged for the processing of the screening fines material by sintering the appropriate substances from it into earth construction material. Sintering can be carried out in the temperature area 600-1,100 °C according to an embodiment of the invention, in a manner dependent on the composition of the reactant, so that actual sintering is achieved and the fusing of the non-combustible matter is avoided.

According to an embodiment of the invention, the pressure of the sintering drum’s 1.3 rotational axis’s bearing is measured through a sensor in connection with the control centre, in which case, using the energy and/or pressure used for rotation, the mass balance of the sintering drum 1.3 can be determined during the process, especially when the process is run according to a batch processing format embodiment.

According to an embodiment of the invention, the sintering drum is arranged to be rotating so that the sinterable substance can be mixed properly and, further, that the movement maintains it in such a state that it cannot form a cake-like build-up that would make the reaction vessel unfit for use. In the sintering drum, lifting handles can be used for lifting the sinterable material in the rotating movement (w) and thus maintaining the mixing/movement. The sintering process can be adjusted by using the rotation speed (w) of the sintering drum’s rotating movement. In addition, the process can also be adjusted by adjusting the tilt angle of the sintering drum’s rotation axis (f), (Figure 1).

The sintering drum is, for example in Figure 1, illustrated as being tilted (f), whereby the material when the sintering drum rotates at a speed of w is carried towards the shallower end, the reaction vessel’s end, from where the ready sintered material is taken to cool following the sintering reaction.

If required, additional fuel can be fed into the sintering dmm 1.3 at the point additional fuel feed LP, whereby by burning it the internal temperature of the sintering dmm and thereby the forming of the end material can be impacted. Additional fuel can be dosed using the control centre’s controls in order to change the temperature and/or keep it constant in a certain part of the sintering dmm. The feed LP can also be distributed, as applicable, between the different parts of the sintering dmm, whereby the process is easier to manage, especially when the reactant can be very variable in terms of the content of the combustible matter. Thus, a distributed feed can be used to select at which part of the sintering dmm the additional fuel is fed. There may also be several additional fuels, selected based on the preliminary data on the combustion staging and prematerial. The sintering dmm shall be manufactured from a material with a sufficient heat resistance and/or it shall have insulation suited for the purpose so that it is able to maintain the reactor’s 1.3 temperature within an area suitable for sintering. Suitable additional fuels are, for example, biogas and/or fuel oil.

The tracer 13C can be fed at an applicable stage of the process into the sintering dmm if this is desired for the identification of the manufacturer in the embodiment of the invention.

The screening fines material can also contain, in most cases, combustible matter. In this case, the combustible matter can be burned for producing heat in the sintering dmm. If required, the combustion can be initiated by burning additional fuel, for raising the temperature and thereby starting the combustion as such, also in embodiments in which the process has been designed to operate continuously. Similarly, by dosing additional fuel, the temperature can be adjusted by driving it up or down using a suitable ramp, which can be selected using the control centre to be suitable for the fed screening fines material batch and/or its part.

When sintering has as such been taken to the end of the sintering drum, from which the end material is taken to be cooled, the heat released in the cooling can be recovered using heat exchangers. This is illustrated with an arrow from box 2.0, which illustrates the cooling of the end material in the cooling space. The symbol X illustrates the heat exchanger arrangement, the heat received from which is illustrated in the example to be steered in the manner illustrated by the arrows and dotted line ring for use in the prewarming of the additional fuel feed. Heat transfer can be controlled under the control centre, which is illustrated using the dotted line arrow.

Figure 3 illustrates with the marking 2.1, in terms of the process, the removal of material using the discharge conveyor from the actual production area in a sintering facility according to the process. With the discharge conveyor 2.1, the material can be taken, for example, for inspection to quality control and/or for packaging into suitable material sizes in specific material forms and/or for further processing for the manufacture of further-processed materials, such as block-like construction materials.

After sintering, the process is divided into two parts, of which the first is related to the processing and packaging of the material. The second branch is related to the processing of the resulting flue gases, which is illustrated in Figure 4, mainly for reasons pertaining to drawing technique.

In Figures 3 and 4, the same reference numbers are used in the flue gas processing branch.

Flue gas coming from the sintering drum is conducted 301 through the flue gas duct 3.0 to the post-combustion unit 3.1, with which harmful substances released and/or formed through sintering are meant to be burned away. The temperature can be, according to an embodiment, 850 °C and the residence time, for example, 2 seconds in accordance with a Decree on Waste Incineration. If required, an exception can be made to the mentioned values technically, as long as the size and duration of the exception are within the limits allowed by law, in accordance with the norms defined by legislation. The feeding of oxygen is illustrated in Figures 3 and 4 with the symbol O2. According to an embodiment of the invention, the feeding of oxygen can take place at a specific place of the sintering drum, but according to a second embodiment, the feeding of oxygen can take place in stages at several places, according to the progression of the combustion, for example in order to adjust the process temperature and/or achieve complete combustion.

According to an embodiment of the invention, the feeding of oxygen can take place at a specific place of the afterburner, but according to a second embodiment, the feeding of oxygen can take place in stages at several places, according to the progression of the combustion, for example in order to adjust the post-combustion process temperature.

In connection with emission measurement, also the oxygen O2 content can be measured from the smoke stack 3.5.

The temperature of the flue gas is reduced in the cooling unit 3.2, which is arranged according to the heat exchanger arrangement to recover heat, to be used in the feeding of the heat flux X, for example, in the prewarming of the screening fines material and/or the prewarming of the additional fuel feed, as applicable. The temperature can, in this case, be lowered, for example, from a temperature of 1,100 °C to a temperature of approx. 150 °C.

The decline in the temperature of the flue gas can achieve nucleation and the resulting condensation, in which case the forming and growth of particles from the substances in a gaseous phase can initiate, whereby the formed particulate matter can mix, in addition to the pre-existing mineral-containing dust particles and any unburned matter, with the flue gases, forming a flue gas aerosol. The particulate matter can be removed using the dust removal unit 3.3, whereby when air acting as a carrier feeds particulate dust to the dust removal unit.

The dust removal unit 3.3 can be, as applicable, implemented using an ordinary electrostatic precipitator, which is designed to scale based on the reactor plant.

According to an embodiment of the invention, a feed can be taken, if required, from the flue gas scrubber 3.4 following the dust removal unit for the partial feeding of the removed scrubbed material to the dust removal unit using a side flow, for changing the chemical/electrical properties of the surface layer of the dust removed with the dust removal unit in order to increase the removal efficiency.

According to an embodiment of the invention, material removed by the dust removal unit can be fed back to the sintering drum for use as a reactant. In this case, for example, the material can be transported from the ash chamber of an electrostatic precipitator (and/or cyclone, if a cyclone is used additionally or alternatively) to the feeder or feeding conveyor.

According to an embodiment of the invention, also a hose and/or bag-like filter can be used, whose collected particulate matter released by the counter-pressure cleaning period can be used as a feed to the sintering dmm using a suspended flow. In this case, also the collected particulate matter can be taken and transported with a feeding conveyor to the process to be used like a raw material.

When the dust removal has been completed, the flue gases are conveyed further to the flue gas scrubber 3.4, in which, as applicable, sulphur and/or nitrogen oxides are removed from the flue gas, and other material that is removed during the scrubbing process. As such, the flue gas scrubber can be an ordinary flue gas scrubber consistent with prior art, without limiting its type as such. Any precipitate building up from the flue gas scrubber can be used, as applicable, as a feed fed back to the sintering dmm.

When the flue gases have been scmbbed, they can be conducted into the smoke stack 3.5. According to an embodiment variant, an emission measurement has been arranged in connection with the smoke stack, whereby, using a gas analyser, for example, gaseous flue gas components, such as, for example, sulphur and nitrogen oxides, can be monitored. Particle emissions can also be monitored with an opacity meter, for example. The measurement results of the meters can be recorded and/or used in the control of the process as control parameters, as applicable, for example for the adjustment of the sintering dmm’s and/or afterburner’s temperature based on nitrogen oxides and/or for adjusting the operation of the flue gas scmbber 3.4, even though an illustrative arrow has not as such been drawn between the boxes.

Figure 5 illustrates a control centre for managing a process according to an embodiment of the invention for the manufacture of earth construction material from screening fines material. According to an embodiment of the invention, the control centre has a microprocessor mR and for this purpose a memory M for its use and a communication network C, for the communication of data between the process actuators T.E1, T.E2 and/or their related sensors Al, A2 for controlling the process. The memory can contain, as applicable, a read-only memory and random-access memory.

Figure 5 refers to the actuator groups T.E1, T.E2 and T.E3 in the controls of the process according to an embodiment of the invention using the process reference numbers used by Figures 1 (T.E2, A2) and 3 (T.E1, Al), whereby, using the reference, Figure 5 illustrates the feedback between each actuator (groups T.E1, T.E2 and T.E3) and the sensor (corresponding sensor groups Al, A2 and A3) that monitors its or the process’s state, corresponding to the actuator group reference of the process stage under the number reference. In this case, the feedback can be, as applicable, direct, but according to an embodiment, the feedback loop has the control centre participating in making decisions using a microprocessor mR (used by an operator according to an embodiment variant), using the process monitoring algorithm in the memory M. The feedback loop can be, as applicable, implemented by using channel C of the communication network for signalling, which is, according to an embodiment, as applicable, a two-way communication channel for the relaying of electrical signals between the reactor plant’s electromechanical actuators, actuator groups and/or the control centre.

In the process, also the temperature, pressure and/or gas flows are measured (the mentioned values can be measured, for example, air/oxygen feeds according to their staging, flue gas flow and similar conditions for each actuator at an actuator-specific location of the process).

The sintering drum’s temperature Ts, and the afterburner’s temperature Tj can be measured, but also the flue gas temperature Tk and, if required, also the temperature Tp of the stack and/or the flue gas flowing in it can be measured. In the process, also the sintering drum pressure Ps, and also the afterburner pressure Pj, can be measured, but also the flue gas pressure Pk can be measured and, if required, also the stack flue gas pressure Pp. The velocity V can also be measured in the process channel’s mentioned parts, in which the pressure and/or temperature are measured, whereby the measured values refer to the velocities Vs from/to the sintering drum, Vj the flow to/from the afterburner, Vk the velocity of the flue gas in the flue gas duct. There can also be several measurement sensors measuring the same value at different parts of the process, for the relaying of measurement data along the channel C to the control centre.

The symbol w illustrates the measurement and adjustment of the rotation speed of the sintering drum. J 1 , J2 and Jn illustrate in Figure 5 (T.E3, A3) the controlling of screening fines fractions using the control centre’s process control. X illustrates the control of the operation of the heat exchangers to adjust the amount of heat and/or turn on/off using the control centre, and S the feedback for the adjustment/transfer of heat, for example, onto a conveyor and/or to the additional fuel feed under the control centre according to the choice of an algorithm and/or user. The invention’s scope of protection is defined in the following claims. It is, however, obvious to those skilled in the art that the details of the different characteristics of the invention can, to some extent vary, within the general inventive concept, depending on each embodiment of the invention.