Spontaneous Combustion
Spontaneous COMBUSTIONI. Preliminary
Coal is one of the solid fuel consisting of compounds of carbon, hydrogen, minerals and other compounds are compounds found in small quantities in the coal anyway. Coal-forming elements of the most or the most dominant is the element carbon, and this is the dominant element in generating heat as well when coal is burned. Such as fuel-other fuel burning coal also has properties (flammable) where the oxidation reaction occurs either by burning or oxidation resulting from reacting with oxygen in the air. Coal reaction with the oxygen in the air will produce heat which is often called self-heating and heating if it is not controlled, there will be a spontaneous combustion is often called Spontaneous Combustion. Of course it is highly undesirable, because it would be very detrimental. To know more about what is happening or what the cause of self-heating until the occurrence of spontaneous combustion, the following is a global discussion about the causes of the problem.II. Oxidation IssuesBefore experiencing Spontaneous Combustion of coal will undergo oxidation process which is the process of initiation of spontaneous combustion when the oxidation process is followed by a continuous increase in temperature which eventually resulted in spontaneous combustion. Coal reacts with oxygen in the air immediately after the coal is exposed during mining. Reaction rate is larger for lower mainly on coal as lignite and sub-bituminous, bituminous coal, while the upper class or high rank coal, the oxidation will only appear if the coal is exposed in a very long period of time. If the temperature continues to increase coal caused by the "self heating", then this needs to be taken seriously as this will affect the value of the commercial value of the coal, in addition to this it will result in spontaneous combustion of coal that is not our desire because it will hurt and also resulted in environmental damage.At normal temperatures the oxidation rate is very small, and even tended to decrease with the lapse of time, thus the risk of quality degradation due to oxidation is still acceptable within the normal delivery time period (8 hours - 8 weeks). Oxidation is the oxidation of the above is not followed by spontaneous combustion or oxidation at low temperatures, but if the long-term storage in stockpiles decline in the quality of the result is usually not acceptable. Because in addition to chemical degradation, a decline in physical quality coal primarily occurs in lower class or "low rank coal". Here are some of the effect of oxidation on the properties of coal:
PARAMETERS:Specific Energy (MJ / kg dmmf)Maximum Gieseler FluidityHGICarbon% dmmfHydrogen% dmmfOxygen% dmmfYield of Pyrolysis TarVitrinite reflectanceMean SizeVolatile matter% dmmf *Crucible Swelling Number *
EFFECT (DOWN / UP):
DownDownUpDownDownUpDownUpDownDownDown* Some coal showed an increase.III. Spontaneous CombustionAs has been described above that causes the onset of spontaneous combustion is an oxidation reaction that occurs naturally in coal, resulting in heating by itself which then cause spontaneous combustion if not controlled. Spontaneous combustion is warming by itself is slowly becoming self-combustion caused by chemical reactions in the coal locally involving moisture and oxygen. Coal will experience warming by itself whenever and wherever when the coal is stored in the form of "bulk" (piles in bulk) both in the stockpile, bin, above the barge, ship or in the mines. "Self-heating" caused by oxidation of the coal surface in contact with the oxygen in the air. Actually, the heat generated can be stripped away by the heat distribution throughout the coal or into the air and by evaporation of the moisture coal. If the heat generated locally due to oxidation, is greater than the heat loss due to convection or evaporation, the temperature of the coal will continue to increase and eventually catch fire by itself.The possibilities of causes that give rise to spontaneous combustion is a function of:§ Type of coal§ Size distribution of coal§ Levels of moisture in coal§ The degree of ignition temperature on the open air§ Coal Storage System§ Weather§ The duration of storage of coalWhile coal is generally more likely to occur warming by itself (self heating) when the coal is:§ Low rank, especially has a high oxygen levels§ Moisture, has a total moisture content of more than 10%§ Contains sufficient iron pyrite experiencing exothermic reaction with air to produce sulfate.§ Have Ignition degree low temperatures in an open environment.In general recommendation to overcome or minimize the possibility of spontaneous combustion is as follows:§ storage area above that has good drainage§ Prevention of particle segregation in stockpile§ Kompacting coal layer by layer§ Minimization of the wind with the orientation of the stockpile§ height restrictions stockpile§ Closure stockpileExperiment to reduce oxidation of the chemical additive is also widely used and successfully inhibit oxidation.IV. Issues In Berau Coal Spontaneous CombustionLook at the criteria that coal has a higher tendency to warming by itself, then we can conclude that the coal Berau Coal includes coal that has a high propensity for the occurrence of self-heating or "Self Heating" type given us including low rank coal and has a total moisture content average above 10%. However, to inhibit the oxidation and dust we are using chemical additive known by the trade name PIC 103.Although we have used additives to prevent or inhibit oxidation resulting in the heating of coal, when the coal is stored too long in temporary stockpile chemical additive that is added has been eroded because many dissolved by rain water, thus heating or even spontaneous combustion still occurs in our coal. We need to know that the factors which accelerate the oxidation or combustion of coal in storage is the oxygen in the air. The more air or contact with surface coal wind the faster the heating process or the coal burning. Therefore, it may be a way to further reduce the tendency of coal heating than 103 PIC is to minimize the contact of coal with air or wind. For the storage methods and or setting in and out of coal in the stockpile needs to be done well.IV.1 Prevention of Occurrence of Spontaneous CombustionSpontaneous combustion problem is a problem that must be dealt with seriously because of this issue in addition to result in small losses will also result in the destruction of the environment, including health hazard if the smoke from the burning of coal exploited. Spontaneous combustion risk is higher for lower coal leanings. To prevent or at least to minimize the possibility of spontaneous combustion is a good stockpile management. If possible we should avoid the storage of coal in the stockpile, as far as possible in the loading of coal to be cultivated fresh from the mine, so storage distockpile solely to determine the quality of the coal before the coal is loading. The more fresh the better because the coal is less likely to occur than the spontaneous combustion of coal is also the quality is still good, and this is the most effective means of prevention for spontaneous combustion problems. However, in practice we often can not avoid the storage of coal in the stockpile for several reasons. It is therefore safe storage procedures need to be implemented to avoid or at least to reduce the possibility of spontaneous combustion.In general, the way to reduce the risk of spontaneous combustion is a coal heap compaction (compacting). However, for some types of coal which has a particularly high value of HGI index, compaction will cause new problems, namely automatic dust size distribution mainly affects the particle size below 2 mm. As with coal Lati, who has averaged 52 HGI, coal is relatively fragile, when in padatkan layer by layer it could lead disintegrate into particles so small (fine coal) that much when in a dry state will lead dust problems ( dust problem). Binungan HGI coal has a lower index of about 40-44 so that coal is relatively harder than Lati coal, coal nevertheless experience Binungan also experienced the same thing that is done when the compaction layer perlapis the size distribution of fine particles becomes so great that eventually lead to problems of dust and fine grain size issues. For the compaction techniques for coal Binungan which may still be applied is the compaction of the layer, ie compaction is performed after the coal is piled high with a maximum. So in fact the purpose of compacting the heap above is to flatten the upper surface so that it does not culminate-punacak because these peaks greater tendency to occur spontaneos combustion. Here is a procedure that may be performed in order to attempt Prevention of spontaneous combustion.§ Drainage must be good stockpile area§ Form stockpile should be elongated in the direction of the wind so that the surface winds are dealing with a small area that is part of the stockpile in width (see Figure -1)§ The surface facing the wind direction must condense and be at a minimum tilt angle around 30-40 degrees.§ The upper surface of the stockpile was also razed, to avoid the small peaks above the surface.§ Preparation of stockpile or coal piles should be arranged so that out of the (first-in-first-out) in its coal stockpile regularly with no problems ignoring quality.§ If the stockpile is stored in a long period of time then the stockpile must be in spray or sprayed with a solution of PIC to the entire wetted surface stockpile. Spraying is done regularly in a certain period eg every 2 or 3 weeks.§ regular temperature monitoring should be done at least after the coal stacked in the stockpile for 3 weeks.It must be emphasized once again that the Prevention of the most effective is not storing coal stockpile too long.If the temperature keeps rising to about 55 ° C after the preventive measures, the mitigation is to re-stockpiling, stacks demolished to evaporate moisture and cool temperatures as well as cooling or coal. In this way the heat generated from the self-heating will be down due to heat convection to the air and water evaporation which also absorb heat. After re-stacking, preventive measures procedure as above was repeated, and after that the new stack dispray with PIC solution for wetting as well as to inhibit oxidation. With the steps above, the coal will hold distockpile rather long periods without burning occurs, but the problem that may arise is the fragility of coal if stored too long. So basically distockpile coal heating could still be reduced by at least mitigated the risk of burning. While the warming that occurred in the coal barge that has been very difficult to overcome the above because we can not let down heating (self heating) with re-stacking or stacking back, as a result of local self-heating that occurs will be greater than the heating lost due to evaporation and or convection heat, consequently the coal temperature will continue to rise. In addition, wind or air above the river or ocean tend to be larger so it will speed up the oxidation process and if allowed to continue, will result in spontaneous combustion. Therefore delay the barge that has been contained for too long should be avoided as far as possible.Basically the exact cause of spontaneous combustion is difficult to predict because there are several factors that are changing or uncertain, such as the weather, the nature of the coal itself as an example; coal has a high sulfur content and low degrees of ignition temperature higher propensity for self-heating occurs or even occurrence of spontaneous combustion. However, other factors must have been like; storage duration, wind, etc., we can still try to be reduced by implementing the recommended storage procedures.IV. 2 Preparation of Form StockpileSee Suaran stockpile locations are located on the river bank, then making a nice stockpile is elongated to form a 90 ° angle to the direction of flow of the river, because the average wind direction likely to come from the direction of the river, especially for wide rivers. So that the width of the stockpile overlooking the river. And the width of the river overlooking the slope should be minimized and also compacted see (figure-1). Then the top surface so that there is stockpile flattened peaks are usually smaller because of the buildup. For smoothing the surface of the pile, done once after the coal stacked with maximum height, whereas the stack height can be higher than 3 m according to the amount of coal that will be kept a bit long in the stockpile. The roller or compactor that is recommended by the tire compactor with a compactor wheels or tires are made of rubber, such as wheel loaders. This is merely meant to lessen the degradation of particles, since the coal at the time of unloading at the boat, didozer to assist with setting unloadingnya grab. So if in the stockpile as well as using steel compactor dozer, then the possibility of degradation of the particles will be greater. Thus the use of tire distockpile compactor will reduce the risk. PIC then spraying on a regular basis to be better made a sprayer installations around the stockpile area.In addition to making a stockpile form as above is no less important is the storage management system. Setting out the entry or first-in, first-out of the coal should be acutely aware that not long until the longer while the new ones are stacked instead taken first. This would result in a risk to the first coal stacked distockpile because the longer duration of time. Of course these settings by not ignoring quality issues. So for quality reasons, there could be no sequential retrieval as described above. Due to the quality problem is not negotiable.Indeed, the future of storage is probably almost inevitable given the volume loading capacity will be on the increase, while mine can not suddenly directly meet market demand, as well as problems that limited mining capacity, also the increasingly stringent quality problems that coal would have to know the quality diloading advance with certainty. Risk if the barge was loading directly into quality problems will not be controlled even gamblingnya element. Meanwhile, the temporary storage will facilitate the blending quality setting, and quality control to achieve customer demand. Therefore stockpile management is absolutely necessary and will be useful to overcome or at least reduce the risk of loss of quality due to storage. However, the above procedures still need to be studied for its application because after the application of the procedure must be tailored to the characteristics of the coal itself, we sometimes compare with other application systems in place that really can not be compared in absolute as possible characteristics or different classes of coal. The procedure above is just general framework of the procedure, while the spesific and the effect will be found during the application process. Indeed, we consider that in practice we are often faced with the problem of cost considerations, double handling and so on.IV. 3 P.I.CPIC is one of the organic compound commonly used as a wetting agent for coal and controlling oxidation agent. Organic compounds generally contain a surfactant, humectant, and emulsion polymer.IV. 3.1 SurfactantSurfactant function to improve wetability of coal, because as we all know that coal is a non polar organic so that the surface tension at once as a result of the coal hard coal once moistened with water. With surfactant molecules in the cluster have radicals hydrophilic and hydrophobic able to lower the surface tension so that the coal can be wetted with water well, and therefore the fine coal particles will be bound with the well water will control coal dust. Mechanisms of surfactant function can be chemically can be described as follows:At the time of surfactant touching hard surfaces wetted coal, hydrophobic radicals will be absorbed on the surface of the coal while hydrophilicnya radicals will form readily wetted surface, so the surface of the coal to be easily wetted.
Coal is one of the solid fuel consisting of compounds of carbon, hydrogen, minerals and other compounds are compounds found in small quantities in the coal anyway. Coal-forming elements of the most or the most dominant is the element carbon, and this is the dominant element in generating heat as well when coal is burned. Such as fuel-other fuel burning coal also has properties (flammable) where the oxidation reaction occurs either by burning or oxidation resulting from reacting with oxygen in the air. Coal reaction with the oxygen in the air will produce heat which is often called self-heating and heating if it is not controlled, there will be a spontaneous combustion is often called Spontaneous Combustion. Of course it is highly undesirable, because it would be very detrimental. To know more about what is happening or what the cause of self-heating until the occurrence of spontaneous combustion, the following is a global discussion about the causes of the problem.II. Oxidation IssuesBefore experiencing Spontaneous Combustion of coal will undergo oxidation process which is the process of initiation of spontaneous combustion when the oxidation process is followed by a continuous increase in temperature which eventually resulted in spontaneous combustion. Coal reacts with oxygen in the air immediately after the coal is exposed during mining. Reaction rate is larger for lower mainly on coal as lignite and sub-bituminous, bituminous coal, while the upper class or high rank coal, the oxidation will only appear if the coal is exposed in a very long period of time. If the temperature continues to increase coal caused by the "self heating", then this needs to be taken seriously as this will affect the value of the commercial value of the coal, in addition to this it will result in spontaneous combustion of coal that is not our desire because it will hurt and also resulted in environmental damage.At normal temperatures the oxidation rate is very small, and even tended to decrease with the lapse of time, thus the risk of quality degradation due to oxidation is still acceptable within the normal delivery time period (8 hours - 8 weeks). Oxidation is the oxidation of the above is not followed by spontaneous combustion or oxidation at low temperatures, but if the long-term storage in stockpiles decline in the quality of the result is usually not acceptable. Because in addition to chemical degradation, a decline in physical quality coal primarily occurs in lower class or "low rank coal". Here are some of the effect of oxidation on the properties of coal:
PARAMETERS:Specific Energy (MJ / kg dmmf)Maximum Gieseler FluidityHGICarbon% dmmfHydrogen% dmmfOxygen% dmmfYield of Pyrolysis TarVitrinite reflectanceMean SizeVolatile matter% dmmf *Crucible Swelling Number *
EFFECT (DOWN / UP):
DownDownUpDownDownUpDownUpDownDownDown* Some coal showed an increase.III. Spontaneous CombustionAs has been described above that causes the onset of spontaneous combustion is an oxidation reaction that occurs naturally in coal, resulting in heating by itself which then cause spontaneous combustion if not controlled. Spontaneous combustion is warming by itself is slowly becoming self-combustion caused by chemical reactions in the coal locally involving moisture and oxygen. Coal will experience warming by itself whenever and wherever when the coal is stored in the form of "bulk" (piles in bulk) both in the stockpile, bin, above the barge, ship or in the mines. "Self-heating" caused by oxidation of the coal surface in contact with the oxygen in the air. Actually, the heat generated can be stripped away by the heat distribution throughout the coal or into the air and by evaporation of the moisture coal. If the heat generated locally due to oxidation, is greater than the heat loss due to convection or evaporation, the temperature of the coal will continue to increase and eventually catch fire by itself.The possibilities of causes that give rise to spontaneous combustion is a function of:§ Type of coal§ Size distribution of coal§ Levels of moisture in coal§ The degree of ignition temperature on the open air§ Coal Storage System§ Weather§ The duration of storage of coalWhile coal is generally more likely to occur warming by itself (self heating) when the coal is:§ Low rank, especially has a high oxygen levels§ Moisture, has a total moisture content of more than 10%§ Contains sufficient iron pyrite experiencing exothermic reaction with air to produce sulfate.§ Have Ignition degree low temperatures in an open environment.In general recommendation to overcome or minimize the possibility of spontaneous combustion is as follows:§ storage area above that has good drainage§ Prevention of particle segregation in stockpile§ Kompacting coal layer by layer§ Minimization of the wind with the orientation of the stockpile§ height restrictions stockpile§ Closure stockpileExperiment to reduce oxidation of the chemical additive is also widely used and successfully inhibit oxidation.IV. Issues In Berau Coal Spontaneous CombustionLook at the criteria that coal has a higher tendency to warming by itself, then we can conclude that the coal Berau Coal includes coal that has a high propensity for the occurrence of self-heating or "Self Heating" type given us including low rank coal and has a total moisture content average above 10%. However, to inhibit the oxidation and dust we are using chemical additive known by the trade name PIC 103.Although we have used additives to prevent or inhibit oxidation resulting in the heating of coal, when the coal is stored too long in temporary stockpile chemical additive that is added has been eroded because many dissolved by rain water, thus heating or even spontaneous combustion still occurs in our coal. We need to know that the factors which accelerate the oxidation or combustion of coal in storage is the oxygen in the air. The more air or contact with surface coal wind the faster the heating process or the coal burning. Therefore, it may be a way to further reduce the tendency of coal heating than 103 PIC is to minimize the contact of coal with air or wind. For the storage methods and or setting in and out of coal in the stockpile needs to be done well.IV.1 Prevention of Occurrence of Spontaneous CombustionSpontaneous combustion problem is a problem that must be dealt with seriously because of this issue in addition to result in small losses will also result in the destruction of the environment, including health hazard if the smoke from the burning of coal exploited. Spontaneous combustion risk is higher for lower coal leanings. To prevent or at least to minimize the possibility of spontaneous combustion is a good stockpile management. If possible we should avoid the storage of coal in the stockpile, as far as possible in the loading of coal to be cultivated fresh from the mine, so storage distockpile solely to determine the quality of the coal before the coal is loading. The more fresh the better because the coal is less likely to occur than the spontaneous combustion of coal is also the quality is still good, and this is the most effective means of prevention for spontaneous combustion problems. However, in practice we often can not avoid the storage of coal in the stockpile for several reasons. It is therefore safe storage procedures need to be implemented to avoid or at least to reduce the possibility of spontaneous combustion.In general, the way to reduce the risk of spontaneous combustion is a coal heap compaction (compacting). However, for some types of coal which has a particularly high value of HGI index, compaction will cause new problems, namely automatic dust size distribution mainly affects the particle size below 2 mm. As with coal Lati, who has averaged 52 HGI, coal is relatively fragile, when in padatkan layer by layer it could lead disintegrate into particles so small (fine coal) that much when in a dry state will lead dust problems ( dust problem). Binungan HGI coal has a lower index of about 40-44 so that coal is relatively harder than Lati coal, coal nevertheless experience Binungan also experienced the same thing that is done when the compaction layer perlapis the size distribution of fine particles becomes so great that eventually lead to problems of dust and fine grain size issues. For the compaction techniques for coal Binungan which may still be applied is the compaction of the layer, ie compaction is performed after the coal is piled high with a maximum. So in fact the purpose of compacting the heap above is to flatten the upper surface so that it does not culminate-punacak because these peaks greater tendency to occur spontaneos combustion. Here is a procedure that may be performed in order to attempt Prevention of spontaneous combustion.§ Drainage must be good stockpile area§ Form stockpile should be elongated in the direction of the wind so that the surface winds are dealing with a small area that is part of the stockpile in width (see Figure -1)§ The surface facing the wind direction must condense and be at a minimum tilt angle around 30-40 degrees.§ The upper surface of the stockpile was also razed, to avoid the small peaks above the surface.§ Preparation of stockpile or coal piles should be arranged so that out of the (first-in-first-out) in its coal stockpile regularly with no problems ignoring quality.§ If the stockpile is stored in a long period of time then the stockpile must be in spray or sprayed with a solution of PIC to the entire wetted surface stockpile. Spraying is done regularly in a certain period eg every 2 or 3 weeks.§ regular temperature monitoring should be done at least after the coal stacked in the stockpile for 3 weeks.It must be emphasized once again that the Prevention of the most effective is not storing coal stockpile too long.If the temperature keeps rising to about 55 ° C after the preventive measures, the mitigation is to re-stockpiling, stacks demolished to evaporate moisture and cool temperatures as well as cooling or coal. In this way the heat generated from the self-heating will be down due to heat convection to the air and water evaporation which also absorb heat. After re-stacking, preventive measures procedure as above was repeated, and after that the new stack dispray with PIC solution for wetting as well as to inhibit oxidation. With the steps above, the coal will hold distockpile rather long periods without burning occurs, but the problem that may arise is the fragility of coal if stored too long. So basically distockpile coal heating could still be reduced by at least mitigated the risk of burning. While the warming that occurred in the coal barge that has been very difficult to overcome the above because we can not let down heating (self heating) with re-stacking or stacking back, as a result of local self-heating that occurs will be greater than the heating lost due to evaporation and or convection heat, consequently the coal temperature will continue to rise. In addition, wind or air above the river or ocean tend to be larger so it will speed up the oxidation process and if allowed to continue, will result in spontaneous combustion. Therefore delay the barge that has been contained for too long should be avoided as far as possible.Basically the exact cause of spontaneous combustion is difficult to predict because there are several factors that are changing or uncertain, such as the weather, the nature of the coal itself as an example; coal has a high sulfur content and low degrees of ignition temperature higher propensity for self-heating occurs or even occurrence of spontaneous combustion. However, other factors must have been like; storage duration, wind, etc., we can still try to be reduced by implementing the recommended storage procedures.IV. 2 Preparation of Form StockpileSee Suaran stockpile locations are located on the river bank, then making a nice stockpile is elongated to form a 90 ° angle to the direction of flow of the river, because the average wind direction likely to come from the direction of the river, especially for wide rivers. So that the width of the stockpile overlooking the river. And the width of the river overlooking the slope should be minimized and also compacted see (figure-1). Then the top surface so that there is stockpile flattened peaks are usually smaller because of the buildup. For smoothing the surface of the pile, done once after the coal stacked with maximum height, whereas the stack height can be higher than 3 m according to the amount of coal that will be kept a bit long in the stockpile. The roller or compactor that is recommended by the tire compactor with a compactor wheels or tires are made of rubber, such as wheel loaders. This is merely meant to lessen the degradation of particles, since the coal at the time of unloading at the boat, didozer to assist with setting unloadingnya grab. So if in the stockpile as well as using steel compactor dozer, then the possibility of degradation of the particles will be greater. Thus the use of tire distockpile compactor will reduce the risk. PIC then spraying on a regular basis to be better made a sprayer installations around the stockpile area.In addition to making a stockpile form as above is no less important is the storage management system. Setting out the entry or first-in, first-out of the coal should be acutely aware that not long until the longer while the new ones are stacked instead taken first. This would result in a risk to the first coal stacked distockpile because the longer duration of time. Of course these settings by not ignoring quality issues. So for quality reasons, there could be no sequential retrieval as described above. Due to the quality problem is not negotiable.Indeed, the future of storage is probably almost inevitable given the volume loading capacity will be on the increase, while mine can not suddenly directly meet market demand, as well as problems that limited mining capacity, also the increasingly stringent quality problems that coal would have to know the quality diloading advance with certainty. Risk if the barge was loading directly into quality problems will not be controlled even gamblingnya element. Meanwhile, the temporary storage will facilitate the blending quality setting, and quality control to achieve customer demand. Therefore stockpile management is absolutely necessary and will be useful to overcome or at least reduce the risk of loss of quality due to storage. However, the above procedures still need to be studied for its application because after the application of the procedure must be tailored to the characteristics of the coal itself, we sometimes compare with other application systems in place that really can not be compared in absolute as possible characteristics or different classes of coal. The procedure above is just general framework of the procedure, while the spesific and the effect will be found during the application process. Indeed, we consider that in practice we are often faced with the problem of cost considerations, double handling and so on.IV. 3 P.I.CPIC is one of the organic compound commonly used as a wetting agent for coal and controlling oxidation agent. Organic compounds generally contain a surfactant, humectant, and emulsion polymer.IV. 3.1 SurfactantSurfactant function to improve wetability of coal, because as we all know that coal is a non polar organic so that the surface tension at once as a result of the coal hard coal once moistened with water. With surfactant molecules in the cluster have radicals hydrophilic and hydrophobic able to lower the surface tension so that the coal can be wetted with water well, and therefore the fine coal particles will be bound with the well water will control coal dust. Mechanisms of surfactant function can be chemically can be described as follows:At the time of surfactant touching hard surfaces wetted coal, hydrophobic radicals will be absorbed on the surface of the coal while hydrophilicnya radicals will form readily wetted surface, so the surface of the coal to be easily wetted.
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