In order to better explain this effective system of Fog Cannon® we will tell you some successful operations where Fog Cannon® was used:

CAVE PEDOGNA

In this historic region of Tuscany, the location of famous cities such as Florence, Siena and Pisa, there is a quarry s active 300 days of the year, extracting materials from a hill under a concession from the Italian government.
 
This quarry has two types of problems related to dust:
1. dust raised following the detonation of dynamite charges.
2. dust raised by the wind that lashes the face of the quarry.
 
In order to solve these two problems, we were contacted by the owner of the quarry, Mr. Lumini, who asked us to perform a test with an FC100 unit to verify the effectiveness of our equipment.
In fact, the alternative proposed by the local government authorities was to reduce the number of excavation days from 300 to 200 per year, with obvious serious economic damage for the quarry, which would have had to reduce its income by about a third.
 
We immediately realized the seriousness of the problem and the difficulties connected to it due to the surface extent of the quarry, which has a 6 Km long face.
 
In order to determine the size of nozzle we had to mount on the test FC, we first analyzed the granulometric composition of the volatile dust present in the quarry, which varied from 0 to 90 µm. This measurement was needed because the micro-drops of the micro-fog must have the same size as the dust participles they come in contact with.
In other words, the following relationship must exist: 

drop size of the micro-fog on impact = granule size of the emitted dust. 

In fact, it should be observed that the dust remains suspended because the turbulent motion of the air is able to oppose the pull of gravity on the individual micro-particles; for this reason, the dust micro-particles need to form aggregations with sufficient mass to fall to the ground. This occurs thanks to the contact between the micro-drops of the micro-fog, which surround the dust particles, favoring their aggregation with other particles. If, however, the dimensions (and, thus, the mass) of the micro-drop were too large, these would be ineffectively washed away; on the other hand, dimensions that are too small would make it impossible to capture the dust. 

For the purpose of obtaining the right sized micro-drops, we had to evaluate an additional, not insignificant, factor due to the location and exposure of the quarry: evaporation.
In fact, water evaporation significantly reduces the mass of the micro-fog particles in their journey from the FC to the point of use; for this reason, we needed to produce micro-particles that were 25% larger at the point of departure, which is to say the nebulizer of the FC. 

We decided that we would need a dozen FCs, with a minimum throw of 200 meters in order to adequately cover the form of the quarry from above. At any rate, along this entire throw we should see no alteration in either the size or density of the micro-drops of the micro-fog. 

Since we were certain of the outcome of the test with the FC100, we immediately began designing an FC200 machine with characteristics that will be better explained below.
In fact, as soon as the test FC100 was mounted in the field, the owner, Mr. Lumini, demanded that we leave it in place until the arrival of the FC200, which he ordered on the spot, ten minutes after we started up the FC100. 

Since the quarry uses dynamite charges, an electric FC200 cannot be used, but it5 must be hydraulically driven by a diesel engine. The FC200s are mounted so as to be attached to a rigid, easily transportable frame.
These are the characteristics of the machine: a 420-kW Caterpillar diesel engine, constructed with a special oil case, directly from Peoria, IL, U.S.A.
A 2600-mm impeller with nine clockwise blades…
 
The construction of the FC200, as described here, took 6 months. When it was turned on the first time, it became obvious to all that the power of the machine was such as to modify the local weather conditions, since, once installed on the top of the hill, it was able to make it rain, even at the height of the summer and with very high temperatures. 

Thanks to the experience we have gained with this particular machine, we are able to describe its more effective applications for solving the problems for which it was designed and constructed:

• Dust Suppression when the dynamite charges are set off
• Dust Suppression along the vast face of the quarry.

In the first case, the FC200 must be turned on at least 25 minutes before the explosion of the charge, to provide the surface soil with sufficient holding power. Then, the FC200 must be left running for the entire period of the explosions and at least 25 minutes after the end of the dynamite explosions.
This turns out to be particularly useful because it has often happened that the dust generated by the explosions is partly sucked into the FC200 and, thus, instantaneously knocked down by the jet of the FC itself. By leaving the FC operating before, during and after the explosions, the result is doubly effective in all senses and directions.
On the other hand, the second application is much simpler and more direct to realize since it is enough to turn the FC200 on for 1 hour for every 6 hours of excavation of the face of the quarry, i.e., one or two times a day. In addition, since only filtered water is used for the micro-fog, it is not necessary to interrupt extraction operations. 

We have been building at least one new FC200 every year for our customer and this for, at least, the last six years. 

And last, but not least, there is the water saved thanks to the FCs.
Before, in the same quarry, they used nine irrigators with a water consumption of 156,000 l/h each, for a total of about 1,386,000 l/h and scant effectiveness in reducing dust. Today they consume 60,000 l/h for each FC200, equal to 360,000 l/h when the equipment will be complete with all six FC200 that were ordered, with dust abatement effectiveness of 80%.

FONDERIE LUCCHINI

FONDERIE LUCCHINI of Trieste is located facing the port on the Adriatic sea to facilitate the unloading of the raw materials necessary for the operations of the foundry, such as: coal, pet coke and iron ore.
This industrial complex dates from 1816. Since then it has been modernized over the years, always remaining the most important industrial complex in northeastern Italy, but also for the Austrian and Czechoslovakian markets.
This plant is, thus, of strategic importance for the economy of the European region it serves.
The area’s weather conditions are extremely difficult since the winds that blow from the sea towards the land (the fearsome “Bora”) can frequently reach 120 Km/h.
In this stockpile where raw materials are piled up to 20 meters high with sides inclined at their specific natural declivity or angle of rest, the management of the plant has always had to confront two types of problems: 

1.pollution of the part of the City of Trieste behind the port, which is colored by the materials stored there;
2.the loss of up to 35 tons of material per year that, even though pulverulent, has already been paid for by the foundry.

To help solving these problems, the company’s management contacted us, in the person of Mr. Pizzoli, who asked us to provide one of our demo units for a test.
The morning of the test, the wind was only blowing at 30 Km/h and the sky was clear. From the top of the piles you could clearly see plumes of dust lifted by the wind with a swirling motion before being completely carried away.

In these particular conditions, Dust Suppression is effective thanks to three distinct actions:
 
1.The first consists of nebulization using a line of Fog Cannons arranged upwind of the piled material, installed at a distance of FCx (depending if 25/50/100/200 meters) from each other, with an elevation arc1.of 90° and a synchronous “fan” motion, as if they were enormous windshield wipers with a height equal to FCx.
This type of action effectively prevents the formation of dust because it exploits the wind – the initial cause of the problem - as the transport vehicle for the micro-fog. In this way, the micro-fog is deposited on the piles with the same intensity as the wind and, thus, using hydrostaticity and the law of the attraction of masses to "glue" the dust to its pile.
This action does not lose its effectiveness even if the micro-fog dries up, since the dust tends to remain on the pile anyway.

2.The second possible action is to prevent the dust from rising in the first place: immediately after the material pile is formed and before the wind can raise particles, a micro-fog must be nebulized, mixed with a 4-6% binder mixture. In fact, the distribution of micro-fog + ECS 89 binder on the piles at rest allows the formation of a surface crust on the walls of the piles that varies from 50 to 500 mm thick. When this surface crust dries, it becomes a sort of roof for the pile that can remain effective for up to 48 weeks, depending on the intensity of the rain. The crust turns out to be so thick thanks to the fact that the micro-fog does not wash off the face of the piles, creating those obvious rills or creeks, such as those created by the irrigators, which wash the walls of the piles with water and simply shift the problem of raising dust from the top to the pavement.

3.The third action is useful in recovering the material where the bottom of the reclaimer or the blade of the bulldozer are taking the material placed in storage.
In this particular case, the dust is released by the inside face of the pile that was never “treated” before. To solve this problem, two FCs (usual FC25s or FC50s) are applied, one on each side of the reclaimer wheel or on the two sides of the face of the pile in the case of a bulldozer, so as to precipitate the dust as it rises and amalgamate it with the material itself. 

These three actions were explained to FONDERIE LUCCHINI before the beginning of the test.
We then brought the demo FC50 into position by towing with a 4x4 and we sprayed the walls of the piles with a 10% mixture of bonding agent and water because the wind was soon to reach a speed greater than 100 Km/h.
When the operation was completed, we verified that, in fact, the crust layer that had formed was between a minimum of 50 mm and a maximum of 500 mm.
On the following days, the wind arose with significant intensity, but this notwithstanding, nothing escaped from the pile.
Thanks to this extremely convincing test, and to our great satisfaction, Mr. Pizzoli immediately asked his purchasing department to order several FCs.