Faced with the choice of the dredger people who had no previous experience of operating such equipment, often fall into a state of utter confusion. They start frantically calling all the offices which they found on request "dredge" on the Internet. On the other end of the sales staff, trying to put his company as the best, tell the tale of the super performance of dredgers manufactured. I have seen these "storytellers" who claim that their pumps pump pulp with the concentration of solids to 80% by volume. They start frantically calling all the offices which they found on request "dredge" on the Internet. On the other end of the sales staff, trying to put his company as the best, tell the tale of the super performance of dredgers manufactured. I have seen these "storytellers" who claim that their pumps pump pulp with the concentration of solids to 80% by volume.

You'd be surprised, but the spread of dredgers performance is extremely high. So one Ukrainian manufacturer offers a manual micro-dredger with hydro loosening, able to pump up to 1 cubic meter of soil per hour. It can be successfully applied in the private farms, when you need to clean the pond in the garden. At the same time, large-scale dredging in marine waters used mastodons with capacity up to 5000 cubic meters per hour of hard ground (dredgers Cristóbal Colón and Leiv Eiriksson «Jan De Nul» company).

I will try to help in deciding how to calculate for you the necessary performance of water-ground mixture dredger.

Let's calculate the amount of the pulp on a concrete example. Take the sand pit with a volume of stocks of 2 million cubic meters of mineral. The quarry is located in the climatic zone where the temperature is positive within 6 months of the year. The owner wants to develop a career of the entire volume of soil for 5 years. He intends that the staff and equipment, respectively, will work in 2 shifts of 8 hours 5 days a week.

#### Step 1. Determine the total number of working days.

Per month on average 21 working days, multiplied by 6 months, we see that for the year the quarry will work 126 days and for the 5 years 630 days respectively.

#### Step 2. The daily rate of output.

Define the necessary daily rate of production. To do this, 2 million cubic meters divide by the total number of working days for 5 years (630 days), and we find that 1 day is necessary to produce a minimum of 3,175 cubic meters of sand.

#### Step 3. Effective time of reclamation.

Determine the number of hours per day that are used directly for the reclamation. For this we use the empirical coefficient of 0.67, which shows that 33% of the time in real life, is used for preparation, repairs and other work, and only 67% goes directly to the sand-wash. Multiply 2 interchangeable working day, namely 16 hours in the above ratio, and obtain the effective time of reclamation 1 day - 10.72 hours.

#### Step 4. Performance on the sand.

Next, determine what dredger performance on dry ground is necessary to ensure reclamation 3,175 cubic meters of sand for reclamation effective time 10.72 hours, which will divide the amount of sand at a time: 3175/296 = 10.72 cubic meters per hour of dry.

#### Step 5: Performance of the pulp.

The most difficult operation we will at the last stage performing calculations: determining the required capacity of the dredger slurry or water-soil mixture. To do this, we need to know the category of the planned soil on a scale of "distribution of soils in groups in developing their suction dredger" (Annex № 1.4 to the Public elemental estimate standards for construction and special construction works. Calculation of the volume of work. 81-02-Pr-2001; Approved Order of the Ministry of Regional Development of the Russian Federation of November 17, 2008 N 253).

Suppose that in our career sandy soil belongs to category 1, for the development and movement of one cubic meter of which requires flow of 6.5 cubic meters of water. Multiplying the required amount of dry 296 6.5 get the dredger on water-soil mixture - 1924 or rounded 2000 cubic meters of pulp per hour.

This algorithm can be used to calculate further theoretical investigations in cases where the required capacity dredger is too expensive to purchase, or on the contrary it is necessary to perform the work in a shorter time.