Equipment Selection in Peat Surface Mining

The problem of equipment selection in a peat surface mine is complex. Many features, restrictions and criteria need to be considered. The equipment selection process begins with the initial conception of peat development. For selecting of hydraulic excavators and tractor-semitrailer combination, equipment selection criteria must be determined. These criteria are collected in 3 different categories, which are:

- Production criteria

- Peatdeposit parameters

- Equipment criteria

Characteristic of hydraulic excavators are a low Nominal Ground pressure (NGP) on the peat deposit surface. Characteristic of tractors&semitrailers are a low Mean Maximum Pressure (MMP) on the peat deposit surface, and high maneuverability (tab. 1). Some kind of limiting value for soft soils is thus MMP=150 kPa (for multiple pass) [3].

 

Tab.1: Effective parameters in selection fleet types

Equipment	Type	Weight,kg	Engine output, W	Bucket capacity, m³	Volume, m³	Track width, mm	Tyres	NGP/ MMP, kPa
Hydraulic excavators	JS-220LC	22 490		1.19				NGP=28.0
Hyundai R210LC-9	22 760		1.34				NGP=32.0
Kraneks EK-270 LC	31 000		1.75				NGP=28.0
Tractors (dual front & rear wheels)	BELARUS 2022.5	7 220					420/70R24- 580/70R42	89.64
John Deere 7730	7 300					480/70R30- 620/70 R42	71.23
Valtra T193	7 300					480/70R30-620/70 R42	71.23
Semitrailers (dual front & rear wheels)	Jaroslavich PS-12B	4 500			11.0		600/50R22.5	139.66
JOSKIN Trans-CAP	4 500			10.2		600/50R22.5	139.66
Bobruisk-agromash PST-9	3 400			10.8		600/50R22.5	132.68

 

 

One of features of peat tractor operation is change of largely bearing and coupling properties of a basic surface of a peat deposit.

Thus, there are the operational factors, which are not allowing completely realizing high potential traction and power properties of wheel mover and engines, which should be considered at justification of rational operating modes and an objective choice of peat equipment.

The peat industry on nature of productions has no analogs in other industries. The principal factor for hauling and loading machines is their capacity. Specifics of peat transport and tractor units and conditions of their operation define the following factors:

- nature of transport operations;

- high deformability and low bearing ability of a peat deposit (tab. 2);

- low indicators of traction and grip of drive tires properties and the increased slipping of tractors on a peat deposit surface;

- basic characteristics and design features of the transport equipment [4].

Tab.2: Peat deposit parameters

Peat type	Degree of decomposition (von Post)	Moisture content,%	Density ρ, kg/m3	Shear strength τ, kPa
Oligotrophic	H4
H5
H6
Eutrophic	H4
H5
H6

The choice of allowed specific ground pressure is defined not only strength properties of a peat deposit surface. With increase in specific ground pressure, the energy spent for overcoming of resistance a crushing of peat increases.

At tractor movement on rather constant trajectories there is a repeated and variable impact on a surface to deterioration of conditions of passability.

Trailer body loading МТ influences transport work. The increase in loading leads to growth of energy expenses on movement and wheels slipping; decrease in loading causes power consumption and decline of productivity.

There are two private criteria of transport efficiency.

1. Minimum of specific energy consumption on unit of transport work

 

(1)

 

where E_T - specific energy consumption, J / (kg · m); N_n - rated-output power of a tractor, W; ξ_n - factor of engine utilization; t_m - movement time with peat, s; L_h - hauling distance, m; M_p - mass of peat in a trailer body, kg; v_t - speed of transportation, m/s.

The analysis of a hauling cycle shows, that the main time of a cycle occupies movement of the loaded and empty semitrailer. Actually time of a hauling cycle is defined by hauling distance (time of movement of the empty and loaded trailer makes from 55 % of a cycle time at hauling distance L _h = 0.5 km and to 85 % - at L _h = 2.5 km). The choice of the rational scheme of placement of stockpiles on a technological plate is an important factor of ensuring efficiency of process of peat raw materials transportation [5].

The mass of peat M _pin a trailer body depends on body volume and density of peat.

2. Criterion of a maximum productivity corresponding to a minimum of energy consumption at movement with peat

 

(2)

 

where P_T - productivity, (kg · m)/s; N_{d max} - the maximum drawbar force of a tractor, W; k_at - specific motion resistance.

As specific motion resistance k _athasa weak dependence on speed, the criterion of P _T corresponds to a maximum traction efficiency and traction capacity.

Application of efficiency criteria allow to formulate a problem of efficiency increase of peat transportation and improvement of the transport equipment.

 

Conclusion

These and other technological developments can be a basis for scientific discussions with the purpose of examination and development of new technologies for reaching maximal results for the production of peat raw material. This method of peat raw material excavation with modern equipment is testing now in Leningrad region. As a result of new technology, economy of scale will continue to be an extremely important factor in the competitiveness of the peat industry.

At the final stage, with respect to daily production rate and capacity of each equipment, the required number of each of machines will calculate. At the first, considering production rate, number of excavators is determined and similarly, tractors-semitrailers number will determine with respect to the excavator, production rate, hauling distance and transportation condition.

References

[1] Korpi, J., Mutka, K. and Nyrönen, T. A new peat production concept – results of the development work during 2004-2007, Proceedings of the 13th International Peat Congress Tullamore, Ireland 8 – 13 June 2008.Volume 1. p. 120-122

[2] Mikhailov A., Nagornov D. Peat excavation and drying for factory-made local fuel production – Peatlands in Balance, Book of Abstracts of the 14th International Peat Congress Stockholm, Sweden June 3-8, 2012.

[3] Larminie, J. C. 1992. Modifications to the mean maximum pressure system. JournalofTerramechanics29(2):239-255.

[4] MikhailovA. Peatproductionscaleandequipment selection – Processesandequipment for mineral mining and handling, Proceedings of ISTC, Minsk, 2012. ISBN 978-985-525-893-4

[5] MikhailovA., Telego A.Peatproductiontransport module– Innovation systems of transport planning and management, Proceedings of I ISTC, National Mineral Resources University,Saint Petersburg, 2013.