Skeptics say that no two identical situations in which the dredger may be involved. However, there are general principles for determining the type of equipment for mining and dredging required for a specific task.
Step 1. Do I need a dredger in principle?
The very presence of this issue is often caught by surprise those who have not even thought about the alternative technical solutions of the problem. So dredging micro-basins: ponds, streams, narrow channels with strong banks and dense soil, - is most advisable to make by excavator, which jib is enough to produce the desired profile of the bottom. The second alternative is to use dredger contractors for small quantities of work, or simply rent a dredger. As practice shows, the appetites of the owners of dredgers, offering their services, are comparable and sometimes significantly exceed the cost of acquisition of a new dredger.
Step 2: What the dredger performance should be?
Calculation of performance is described in detail in the article "Step-by-step guide to selecting the dredger performance."
Step 3. Diesel or electrician?
Selection the type of energy source depends on two factors: the availability of electric power and plans to further transfer the dredger to places where are unable to connect to electricity. If the working area of the dredger is possible to connect to the electricity, it is best to choose an electric source. Among the main advantages can be identified are economic efficiency, easy maintenance and fault tolerance of electric motors in comparison with diesel drive.
Diesel dredger is the only possible choice in the absence of the mains. Autonomy is undeniable advantage. For far-sighted owners who appreciate the versatility of their assets, there is a third type of dredger - diesel-electric. In this type diesel power unit produces electricity for all consumers on board. If you can connect to the mains, the dredger operates as an electric, but when you want to work in remote areas, power is supplied by diesel power unit.
Step 4. Type of suction.
Free suction is recommended to use only non-compacted soils with incoherent structure that is found in areas with fresh river sand drifts. Hydro jetting is used for ground, easily disaggregation through a water jet under high pressure. This category soils are 1-3 on the 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). The use of hydro jetting for soils 4-6 categories of this scale are also possible, but the maximum concentration of solids in the slurry on soil category 5 falls to 8.5%, 6 categories to 7.4%, which was not a satisfactory indicator. The soils of these categories seems more appropriate to use the cutter suction, which is the most versatile. The cutters are not an insurmountable obstacle clay lenses in the career, silt and peat, sprouted roots of vegetation. One of the advantages of the cutter is to lower the power consumption on the mining of 1 cubic meter of soil in comparison with jetting that can result in substantial price savings on large production volumes.
For the sapropel extraction it is recommended to use a completely different method, a screw pump. This is combined in a single device suction head and unit for pushing takes sapropel from the bottom in the status of natural moisture and pushes the slurry pipeline in the form of so-called "sausage". The result is a sapropel, ready to be loaded into trucks for further transportation.
Step 5. The slurry pipeline metal or rubber?
The choice of the form of a slurry pipeline is not a difficult procedure. In this case, the main thing is to answer the question, what is more important to you – convenience for staff or capital costs. Metal slurry pipeline on ball joints allows you to organize safe pedestrian message dredger – shore. A more budget option is to use floating rubber slurry pipeline. In more detail, the selection of form of a slurry pipeline will be covered in the article "Selecting the type of slurry pipeline: metal or rubber".
So, we conducted analytical work has determined the basic parameters of dredger, fill out questionnaires on web-sites of dredgers manufacturers and got a bunch of suggestions. It is time to move on to the last stage.
Step 6. Proposals audit.
This stage it is recommended to have a professional who is well versed in the hydrodynamic calculations. Why? You buy a dredger to perform a specific task. It may be sand mining a certain amount of soil per hour. This means that the manufacturer must calculate and pick up for your specific conditions: the soil model pump, the engine with sufficient power, the elements of "strapping". The factors influencing the choice of basic units include: classification of the soil, the required performance on a soil basis, the maximum mining depth, maximum and minimum length of slurry pipeline, geodetic swings and lifting, required minimum pressure at the exit of the pipeline. Practice shows that almost 90% of the offers from manufacturers, there are gross errors, which ultimately may lead to loss of money and buying equipment that just won't pan out the required amount.
If in your state there is no specialist with this qualification or would you like to insure against loss of your investment, you can request an audit of technical and commercial proposals from suppliers. As a result, you will get the dredger, which is guaranteed to perform its tasks.