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Plugging the cement industry's efficiency gap

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World Cement,

Per Hansson, Bruks Siwertell, explains how new levels of efficiency and environmental protection must be adopted if the increasing demand for cement is to be met.

Second only to water, cement is the world’s most widely consumed commodity, and with the global pandemic only stalling its rising consumption, eyes are turning to increases in port handling efficiencies to help meet global demand.

Demand predominantly comes from growing populations and their inherent need for food, energy and infrastructure; the United Nations (UN) predicts that by 2100 the world’s population will be about 11 billion, an increase of 4 billion from today’s levels.

Port terminals are at the face of meeting this challenging rise in dry bulk volumes and it is imperative that handlers adopt equipment that will not just accommodate today’s capacity requirements, but also meet a long-term vision of substantial increases and very strict environmental protection regulations. Equipment should also maximise a terminal’s profitability.

The most cost-efficient way to meet rising bulk demands is to design an optimised terminal. This could be installed from the outset, or through the replacement of out-dated equipment as part of a modernisation programme.

Three main options

Cement handlers have three main technical solutions at their disposal: mechanical, pneumatic, and grab unloaders. Each has their own benefits and limitations, all of which need to be carefully considered when making a choice about long-term efficiency and sustainability.

Pollution is one of the most significant environmental issues in ports, and grab unloaders are under increasing scrutiny. They can lose up to two percent of a shipment through spillage, and are one of the largest culprits for dust emissions in dry bulk handling operations. Material degradation is also a problem. Given the exorbitant imbued carbon costs in cement production, and the imperative for the world to curb its environmental impact, it is likely that replacing these machines will be regarded as a quick-win, and their presence in ports will be greatly reduced.

So, can pneumatics plug the capacity gap? Pneumatic unloaders are restricted to a capacity of about 600 – 800 tph with one pipe when handling cement, for example. To achieve higher capacities, they either need to have two nozzles or two unloaders. In both cases this comes with increased investment costs as well as higher operational costs. These systems work well in ports with low annual intakes, however if an existing or new port terminal needs to expand it is unlikely that they can step up, without considerable cost.

The other element to consider when analysing dry bulk unloading efficiency is hold reach. A pneumatic unloader is very limited in this capacity and the vertical arm can only be operated within the area of the hold opening. There are pneumatic unloaders which have some pendulum movement, but all pneumatics have limitations relating to having very low or no digging force capability. This makes them unsuitable for any compacted bulk. The ability to move within a hold also impacts the necessity for payloader assistance; this can be as high as 18% for some operations.

In comparable conditions, a Siwertell screw-type ship unloader uses less than 5% payloader assistance, and in barges with horizontal walls, the need for a payloader will be below 2%. This is because a Siwertell screw-type unloader can move its vertical arm +/- 30° and reach all areas of the cargo hold, including underneath the hatches, where material can build up.

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