Marmettola : Problem Or Resource
class 2a A
MARMETTOLA : PROBLEM OR RESOURCE ?
We are class 2^ A of Liceo Scientifico Marconi . We are interested in studying a big problem our territory has:” marmettola”. We are following it with our teachers : Vannucci (Scince) and Fregosi (English).
Our geographical area is peculiar because the sea and the mountains seam to touch, the mountains are just a few Kilometres far from the sea (7 Km); look at the picture.
From our mountains, the Apuan Alpes, we extract the most famous marble in the world: Carrara white marble. What is marble?
Marble is a metamorphic rock, consisting mainly of calcious carbonate (CaCO3>95%) aggregated in a crystalline filling which is veined by additional minerals leading, with their veins, to the different varieties.
It is a bright stone (it owes its name to the Greek word “marmario” meaning to shine) which formerly drew the attention of the ancient Romans.
It is the stone used by our greatest sculptors such as Michelangelo and Canova.
Let’s have a look at the following scheme to understand how marble from the mountains reaches its final destination:
As you can see marmettola is produced in the moment in which marble is slabbed.
We can say that marmettola is marble dust mingled with the water that is necessary just to slab the block.
Is marmettola a problem?
It is not a polluting material, yet there is a problem: what to do with marmettola?
It has been sent into the waters of the river Carrione for centuries, but the great quantity of it was becaming a problem.
In the following picture you can see how the waters of the Carrione are milk like in presence of marmettola.
A few years ago it was found out that marmettola can be useful, for example, in a power station.
In La Spezia, a town not far from Carrara, marmettola, together with water, is used in the local power station just to neutralize the dangerous smoke coming out of its chimneys.
That’ why we wander: is marmettola a problem or a resourse?
This is the first part of our work just to let you know what we are studying about.
In the second part we are going to write about some interviews we have planned with local industrialists and workers.
INTERVIEWS
1st Interview; Wednesday 5th April, 2006
Today we paid a visit to the firm S.M.C., which is situated near our school. It is a firm which cuts marble, before polishing it and selling it as slabs. We interviewed the owner, Mr. Babbini, who showed how to work and produce marble slurry.
· Mr. Babbini, how is marble slurry produced by your firm?
The blocks of marble that arrive here come directly from the quarries, and so have not been worked and are large in size. In order to sell marble, before anything else, we have to cut these huge blocks so as to create smaller, rectangular slabs. As a result of the cutting phase, which makes use of water and a diamond-studded wire, there is a residue of whitish water containing powdered marble.
· Where does this whitish water laden with powdered marble end up?
It falls into a well situated beneath the cutting machine, and from there flows into a collection basin, before being pumped into the ‘decantation silos’.
· What is a silo? How does it work?
It is a chamber that serves to separate the water from the marble powder. Thus water comes out of one part, and from the other exits marble powder with just a small remaining amount of water. Let’s go and see ….
What comes out is not yet marble slurry. This is produced by passing the mixture through a filter press, which compacts the powder to produce the true marble slurry.
· How much marble slurry do you produce every day?
Every day we produce about 20 tonnes of marble slurry, and we have to see to the disposal of an enormous quantity of this material, which was considered one of many forms of waste in the past.
· Nowadays it is no longer considered to be waste?
For us it is a by-product of the working of marble, and thus a material in need of disposal, but nowadays there are people who are able to make use of it in an ecological manner.
· Where is your marble slurry disposed of?
It is collected by the firm CAGES in Massa.
Our first interview reached its conclusion at this point. Having become curious regarding the possible uses of marble slurry, the following week we interviewed Mr. Gabarra of the firm CAGES in Massa.
2nd Interview; Wednesday 12th April, 2006
· Mr. Gabarra, we have been told that CAGES collects marble slurry from various firms in the Massa Carrara area; can you explain what you do with this slurry on a daily basis?
It’s not easy to answer this question briefly. Marble slurry can be utilised in a variety of ways, and an in-depth description of all the processes of transformation that the slurry undergoes won’t be simple … but I’ll try to give you a broad idea, making things as simple as possible.
· CAGES collects only marble slurry?
Above all, but not exclusively … some forms supply us with whitish water containing marble powder.
· For what reason?
These firms cannot afford to buy silos and filter presses, so in these cases it’s up to us to produce the marble slurry.
· Let’s go back to the potential uses of marble slurry. Where does your slurry end up?
There are four different destinations: the firm Tioxide in Scarlino (Grosseto), the ENEL plant in La Spezia, cement works and paper mills.
· How does it arrive at its destination?
It is transported by lorries. Every lorry departs from CAGES with a precise quantity of marble slurry.
In fact, prior to departure the lorry has to pass over a weighing machine, and if the load is not as it should be, we see to the adding (or removal) of the appropriate amount of slurry.
· What does Tioxide in Scarlino (GR) do with your marble slurry?
Tioxide produces Titanium Dioxide (TiO2), a non-toxic, white pigment which, to put it simply, gives the whiteness to our white objects. Titanium Dioxide is extracted from a mineral called ilmenite which contains titanium and oxygen, but also iron. Ilmenite comes from mines in Norway, and the first treatment which it undergoes in the Tioxide plant is the removal of the iron, in order to obtain the Titanium Dioxide. This process necessitates the use of Sulphuric Acid (a very strong acid) and as waste, produces a toxic mixture of sulphuric acid and iron. Marble slurry has proved to be an excellent means to eliminate the toxicity of this waste, given that it reacts with the mixture to transform it into ‘red chalk’ (an inert, non-toxic material), also producing water and carbon dioxide, which is subsequently gathered and sold.
· Paper mills also need marble slurry?
Yes, they use it to whiten paper. The white paper used for drawing is always treated with particular substances, and among these is the marble powder from slurry.
We send the purest marble slurry to the paper mills, precisely because it is used for whitening, and thus in our plant we divide the slurry into various categories … here, for example, is a deposit of the purest slurry, ready to be sent to the paper mills.
· Where does the less pure marble slurry end up?
That is sent to the cement works. The cement industry has need not only of slurry, but also of larger pieces of marble waste which we gather from the quarries, put to one side and then transport to the cement works. This is a storage area for material destined for cement works, and as you can see, the piece are much larger than marble powder.
· Finally, please tell us about the ENEL Plant in La Spezia.
The ENEL Plant of La Spezia is an electric power station, which produces electrical energy via combustion. Among the materials used as in this process there is also sulphur. Sulphur combines with oxygen to produce Sulphur Dioxide (S02), which is then released into the atmosphere. The emmision of this substance into the atmosphere is hazardous, given that it causes acid rain. Also in this case marble slurry has proved to be an excellent reagent, in that it is able to eliminate Sulphur Dioxide (S02), transforming it into Calcium Sulphate (CaSO4). The ENEL Plant of La Spezia is very proud of this result, which has led to the cutting of emissions into the atmosphere of threatening sulphur dioxide, exploiting a material which is a residue of the working of marble.
class 2a B
climatic changes
Our study plan in this school is characterised by a chemical, biological and scientific experimentation which aims at studying the environment, especially the environment of our geographic area. That is why the students of class 2B of the “Liceo Scientifico G. Marconi “ found it natural to choose this topic, even though its intrinsic difficulties are obvious. Our school is provided with a meteorological observation station which is quite important in the area. The data on rainfall and temperature, which are collected by it, are sent to the Pisa Ideographic Institute every month. Moreover the same data, together with those concerning wind, are often used by private and public organisations. Therefore we decided to analyse the climate trends of our area in the last 35 years (starting from 1970). Our science and chemistry teacher, Mr Bacciola Domenico, who is also responsible for the meteorological observation station, was our advisor and guide in the project. He provided us with the weekly rainfall figures which were registered in the archives of the observation station. We decided to analyse 2 separate periods: from 1970 to 1990 and from 1991 to 2005. Our choice was motivated by the fact that, if there have been significant climate changes, they started to take place in the early 1990s. Our project will be focused on the analysis of pluviometrical graphs: when anomalies, periods of heavy rainfall and long-lasting intervals without rain are found, the thermic trends before and during these periods will be taken into account.
Year / Rainfall (mm)1970 / 1139 / mm
1971 / 1220 / mm
1972 / 1027 / mm
1973 / 766,6 / mm
1974 / 1181,2 / mm
1975 / 1194,3 / mm
1976 / 1025,6 / mm
1977 / 1423,3 / mm
1978 / 1218,2 / mm
1979 / 1598,3 / mm
1980 / 1136,7 / mm
1981 / 860,1 / mm
1982 / 1041 / mm
1983 / 971,7 / mm
1984 / 1134,3 / mm
1985 / 1066,2 / mm
1986 / 1089,8 / mm
1987 / 1514,5 / mm
1988 / 1400 / mm
1989 / 1286,9 / mm
1990 / 1357,2 / mm
The 1970-1990 pluviometrical figures are represented in the following chart.
Total rainfall (measured in mm) for each year.
mm
1991 / 1191,4 / mm
1992 / 1507,9 / mm
1993 / 800 / mm
1994 / 1271 / mm
1995 / 1312,9 / mm
1996 / mm
1997 / 597 / mm
1998 / 807 / mm
1999 / 968,5 / mm
2000 / 1141,3 / mm
2001 / 987,8 * / mm
2002 / 987,8 / mm
2003 / 1634,2 / mm
2004 / 1052,5 / mm
2005 / 1027,74 / mm
*Does not include June
The 1991-2005 pluviometrical figures are represented in the following chart.From our rainfall statistics, apart from total annual precipitation, it is possibile to report the following features.
1997: / from 30/06 to 31/10 there was 54 mm of rain, with 12 weeks having no precipitation whatsoever1998: / from 19/01 to 31/08 there was only 230 mm of rainfallì
2000: / from 18/09 to 31/12 796,8 mm were recorded, in particular, from 09/10 to 29/11 precipitation amounted to 537 mm
2002: / was the rainiest year amongst those examined, including the exceptional week 16/09 – 23/09, when some 239,6 mm of rain were
recorded
2003: / from 01/01 to 22/09 there was just 351 mm of rain. On 23/09 290 mm of rain fell on our city, of which 140 mm between 19:15 and 20:30, thereby provoking a flood which led to serious damage and, unfortunately, a victim.
Closer analysis of the data leads to several observations:
1.From the middle of the 1990s until 2003, the number of days on which rain fell tended to decrease, whilst the intensity of precipitation increased.
2.Rainfall has tended to shift towards the last 3-4 months of the year, leading to phenomena of major relevance. These pluviometric shifts are a consequence of particular thermal conditions. For example 2002 was characterised by an extremely warm October, which followed a rather dry summer. This was the prelude to an extraordinarily wet November and December. The events of 2003 were without precedence, even in the memory of the most senior citizens. From the first days of May the weather was dominated by the humid heat of the scirocco. It rained on a single day ( for little more than an hour); 31st July. The hot, humid weather then continued, causing numerous victims in Europe, and only occasionally being interrupted by timid showers from the first days of September. 23rd September was “a day of reckoning” in our city. Such an event, however, is not without explanation. In July and August the sea was recorded as being 4°- 5° warmer than the norm; a condition which was ideal for enriching the atmosphere with vapour and energy to an incredible extent. From the summary of data above, the figures for 1996 are missing. It was a year in which nobody took care of the weather station in our school. From local newspapers of the time, and other sources of information, we have discerned that on 19/06, in the higher lands of Versilia, a neighbouring zone, between 7.00 and 13.00 487 mm of rain fell; this being enough to wipe out two villages, Fornovo Casco and Cardoso, as well as causing the deaths of more than ten people. This event can also be explained. For the whole of May, and the first half of June, the temperature was much higher than the norm, without there being a single disturbance that might have mitigated the situation of an atmosphere highly charged with vapour and energy.