The drilling and tunnelling industries rely on the separation of cuttings in order to progress with their activities. Decapress centrifuge designs used in this area mean that a high capacity of feed (typically 1-120 m3/hr) can be processed in a very small footprint.
The Hiller-DDF series is manufactured in our modern factory under the most stringent quality controls. The quality of manufacture is reflected in the satisfaction of our customers.
Hiller decanters have been used for ‘drilling mud’ in vertical exploration drilling for the development of oil and gas fields for more than 20 years.
For over 15 years Hiller decanters have not only been used in horizontal drilling for the development of traffic routes and the construction of roads, railroads, and metro lines but also for drilling supply and disposal tunnels for the management of water, wastewater and energy to clean bentonite, barite, and drilling polymer scavengings when so-called hydro-shield driving techniques are applied.
Even with changed slurry input and flowing conditions in the decanter, new hydraulic drives with a wider speed range and higher oil output allow for the processing of slurry quantities 20% to 50% higher than usual.
Modern tunnel boring machines (TBM) can have diameters of 14 meters and more, and thus enable our civil engineers to design multi-purpose tunnels, with all their economic and environmental benefits. In recent times, the technological trend for tunnel boring machines is increasingly towards the hydroshield technology.
In hydroshield technology, the progressing tunnel is sealed from the tunnel excavation front by means of continuous recirculation of a bentonite slurry. At the same time, this slurry also serves as carrier for removal of the cuttings from the excavation front to the solids separation plant. In the solids separation plant, the cuttings are removed by means of screens and hydrocyclones. The cleaned bentonite slurry is then ready to be recycled to the TBM.
During the vertical drilling process “drilling mud” is produced. This has to be dewatered, which is when a Hiller high performance centrifuge can save time and money.
Tunnel dewatering is the latest field of application for Hiller high performance centrifuges. For this application natural water penetrations are pumped out from the tunnel and are then cleared with Hiller centrifuges.
Economy and quality
Depending on the properties of the soil where the tunnel is being drilled, very fine cuttings can accumulate in the bentonite slurry. This affects the properties of the slurry over time. This negative effect can be monitored by measuring the density of the slurry.
When the slurry density has risen above the acceptable limit, some of the slurry inventory is discarded and replaced with fresh bentonite slurry, in order to maintain the density in the system at the desired level. After having passed through the normal mechanical treatment the discarded slurry is fed to a decanter centrifuge plant for separation and dewatering of the spent bentonite. The dewatered solids can then be sent to land-based disposal, or used with rougher cuttings whilst the clear water can be discharged to sewers and is recycled to the process.
In this demanding application (where reliability is of the highest importance for un-hindered tunnel progress and performance is equally important due to increasingly strict environmental legislation and rising landfill costs), Hiller DDF high performance centrifuges are the first choice.
For vertical drilling applications, Hiller can offer standardised multi-purpose machines, as well as customised designs which are optimised for your specific requirements. Contact us today to find out more about our solutions.