@Peter, thanks for your feedback, you make a very valid point. We offer the anonymous feature to allow people to express themselves freely. We'll be monitoring this closely and will make necessary changes if people start misusing the feature. Thanks again.
Carrying capacity is defined as the mass of concentrate pulled per unit time for a unit surface area of the flotation machine. If using metric system, it is t/h of concentrate produced per m2 of cell (froth) surface area. There are mainly 3 key factors that define carrying capacity of a machine:
Bubble size - This is an important factor in defining carrying capacity and is dependant on the flotation machine. Smaller the bubbles, more is the bubble surface area available per m2 (for particles to attach) and hence higher the carrying capacity.
Particle size distribution - Often, a representative particle size (d80) is used to predict carrying capacity. However, particle size distribution is equally important. The finer the d80 (and/or more the amount of fines in the feed), lesser is the carrying capacity number.
Density - This will vary based on the feed/ ore type. Higher density materials will have higher carrying capacities.
For a given diameter of a flotation cell, you can only recover so much froth/ concentrate based on carrying capacity. Theoretically this is a condition when all the bubbles are fully loaded with particles. This condition is defined as "carrying capacity limit" of the machine.
It should be noted that carrying capacity limit is a design number. The flotation machines should be designed to operate below that number i.e. it should be possible to achieve target recoveries without reaching the carrying capacity limit of the machine.
With time however, the feed characteristics (size distribution and sometimes feed density) change which results in change in actual carrying capacity number, sometimes going over the carrying capacity limit of the machine. I would suggest gathering data around your flotation feed and reaching out to the supplier of flotation machines at your site. They should be able to help with the design limitation of your circuit.
Based on the company you work for, I assume your question is with reference to a shotcrete plant. If I understand this correctly you have a small batch plant installed at surface and use 2 agitator/ mixer trucks to transport the material underground. Some of the high level things I suggest you consider are:
Understand the number of agitators you'll need to meet the requirement of increased output. This should factor in.
The transport distance and a typical turnaround time of the truck (based on the the no. of working hours in a day).
Any restrictions around the vehicle traffic in the accesses of the mine
Calculate the batch cycle time (and no. of cycles) required to meet the trucking capacity. Consider the following points in this.
If there is a central mixer in the plant then its capacity will define the number of cycles required to fill in the intransit agitator truck. If the plant is just a dosing plant, this shouldn't be a problem.
One of the key aspects to bear in mind while looking at the capacity is the homogeneity and quality of the resulting shotcrete.
Based on points 1 and 2, you'll be able to figure out the limitations of your exisiting equipment and what additional equipments are required for you to meet the demand.
You'll also have to factor in addition storage the equipment may need.
The last and yet the most critical one will be additional manpower. You'd need to bring on more trained people (depending on the amount of work) to cater to the increase in scale of the operation. Factor in time for them getting on board, their inductions and certifcations that will be required for them to do the job.
Some of the operations that are currently using (or have used bioleaching in past) at commercial industrial scale are as below.
Acid Mine Drainage (Rio Tinto in Spain)
Dump Leaching (Bagdad, Morenci, Pinto Valley, Sierrita - all in USA)
Heap Leaching (Cerro Colorado in Chile, Cananea in Mexico, Chuquicamata SBL in Chile, Collahuasi in Chile, Girilambone, Australia, Ivan Zar in Chile, Morenci in USA, Punta del Cobre in Chile, Quebrada Blanca in Chile, Salvador QM in Chile, Sociedad Minera Pudahuel in Chile, Zaldívar in Chile)
Bioleaching of Gold Concentrates (Ashanti in Ghana, Fairview in Zambia, Harbour Lights and Mount Leyshon in Australia, Sao Bento in Brazil, Wiluna, and Youanmi in Australia)
"Ex Works" means that the seller delivers when it places the goods at the disposal of the buyer at seller's premises or at another names place (i.e. works, factory, warehouse, etc.) The seller doesn't need to load the goods on any collecting vehicle, nor does it need to clear goods or export, where such clearance is applicable. It is critical to specify as clearly as possible the point within the named place of delivery, as the costs and risks to that point are for the account of the seller. The buyer bears all costs and risks involved in taking all the good from the agreed point, if any, at the named place of delivery.
FCA or "Free Carrier" means that the seller delivers the goods to the carrier or another person nominated by the buyer at the seller's premises or another named place. It is advised to clearly specify the point within the named place of delivery, as the risk passes to the buyer at that point. If the parties intend to deliver the goods at the seller's premises, they should identify the address of those premises as the named place of delivery. If, on the other hand, the parties intend the goods to be delivered at another place, they must identify a different specific place of delivery. FCA requires the seller t clear goods for export, where applicable. However, the seller has no obligation to clear the goods for import, pay any import duty or carry out any import custom formalities.
I have attached a chart of responsibilities under different incoterms which you may find beneficial.
@Peter, thanks for your feedback, you make a very valid point. We offer the anonymous feature to allow people to express themselves freely. We'll be monitoring this closely and will make necessary changes if people start misusing the feature. Thanks again.