Cement Supply for Block Production in Iraq: Silos, Sourcing and Daily Draw

Cement supply for block production in Iraq is decided inside the plant, not at the supplier's office. What matters is how the cement arrives, where it sits before the mixer calls, who signs for it at the gate, and what happens when a load turns up damp. A QSGW line rated 30,000 to 250,000 pcs per 8-hour shift draws cement all shift long, and every hour the silo cannot feed the weighing hopper is an hour the press stands still.

Bulk or bagged, one silo or two, a tanker daily or every second day: each choice moves labour, dust and pallets. Humidity, not the invoice, breaks the flow between deliveries.

Bulk cement and bagged cement do different things to a crew

Bulk cement arrives in a tanker, is blown into a silo, and leaves by screw into the batching hopper. Nobody lifts a bag: one person watches the hose, the filter and the level, and the dust stays inside a closed system. Bagged cement is stacked in a store, slit open by hand and tipped into a hopper, three handling steps per bag, each releasing dust at breathing height.

The labour difference lands on the roster. A fully automatic QSGW line runs on 3 to 6 persons per shift, and none of those posts is a bag slitter. Put bagged cement in front of it and you add a body at the mixer mouth, or the press waits for the next bag. On a 15 to 25 second cycle it does not wait politely, and bagged cement survives only where a tanker cannot turn.

Size the silo against one day of draw, not against a discount

Start from the press, not the tanker. Count the batches the machine runs in a shift at its real cycle, take cement weight per batch from your mix design, and that is the day's draw. The silo holds that figure plus a working heel, so the last hour is not run on an empty silo.

Two failures follow from a wrong size. A silo holding less than a day forces a mid-shift refill, with a tanker at the gate while the line runs and dust beside the cuber. A silo holding weeks keeps a static mass through every humidity cycle, and cement that has stood and compacted is the cement that bridges.

Read the level indicator at each shift start against the planned draw, and order when the margin is one delivery, not one hour.

Why does cement bridge in humid weather?

Bridging is an arch of compacted cement over the silo outlet while the level still reads full. Warm damp air enters through the filter, meets a cooler wall after dark and condenses. Fines stick to the cone, the arch hardens, and the screw runs empty under a healthy level. Basra carries that humidity all summer; Erbil gets it from the day to night swing.

Run the aeration pads before the outlet runs short, not after the weigh hopper reads low, because air has to reach the cement before it sets into a mass. Draw steadily rather than in stop and start bursts, since a silo worked every hour never gets the quiet days an arch needs. Keep the filter and pressure relief clean: a blocked vent pulls moist air through every joint.

Clear a bridge from outside: isolate the screw, use the vibrator or the air pads, and never open a hatch to stand under the cone with a rod.

Cement type and early strength change the curing yard plan

Cement type decides the curing yard more than any machine setting. The number that runs the yard is how long a green pallet must stand before the cuber can lift it. High early strength releases a pallet sooner, a slower cement holds it longer, and that difference becomes pallet count.

The QS-1200A cuber handles about 3,800 pallets per shift, and every one must be free to move. If the cement needs longer before cubing, the queue grows and the plant buys pallets to solve a cement problem. Pallet size on the QST1200 is fixed at 1,350 x 880 x 25 mm, so the footprint is fixed too; only the count tied up in green block changes.

Ambient heat finishes the argument: the same cement sets differently on a July afternoon in Basra and a winter morning in Erbil, and a mix that flashes cracks at the edges when the pallet is lifted.

Who accepts a load at the gate, and what do they sign for?

Name one person per shift and give that person authority to reject a load without calling the owner. A tanker accepted by default sets the quality standard for the month.

Delivery frequency follows the silo, not the supplier's route. A plant drawing a full silo a day takes a load daily; one with two silos takes a full load every second day, halving the tankers and the dust events with them. Fix the pattern in writing and tie it to the production plan, so a quiet week does not leave cement sitting for a month.

Five things are checked on every load before the hose goes on.

• Weighbridge ticket: gross, tare and net against the ordered quantity, not what the driver says.
• Seal on the tanker hatch: the number matches the dispatch note; a broken seal waits outside.
• Dispatch time: cement that left the works days ago and sat in a hot tanker is not what was ordered.
• Temperature of a fresh load: hot from the mill sets faster and can flash in the mixer, cold in humid weather bridges.
• Retained sample: one per load, dated and labelled with the silo number, for a late strength result.

Batching accuracy and the vibration device that protects it

Batching accuracy is a flow problem before it is a scale problem. The PL series batching machine weighs with a three-point induction sensor and doses in two stages, fast to fill most of the target and slow to finish it. That holds while material reaches the gate at a steady rate, and fails when a half bridged silo dumps its cement in one lump: the scale reads the right total while the mixer gets a slug.

The anti-bridging vibration device on the PL batching machine exists for that gap. It keeps material moving across the hopper gate so the two dosing stages have something to control, and it is not a cure for wet cement or a reason to run a silo that needs emptying.

Check the scale against a known load at the start of a campaign and keep the printout. A QST1200 draws 57.6 kW installed and a QST1000 48.9 kW, so silo and aeration blowers are small loads beside the press. The press is rated at 31.5 MPa with 150 kN of vibration force, which describes what it does to a correct mix; a wrong batch gets the same force and fails faster.

Three things are settled on site before anything is ordered, and each belongs on the layout drawing, not in a conversation.

• Cement source: one supplier or two, the distance to the plant, and whether the type stays the same between loads.
• Storage space: a silo needs a foundation, a safe zone around the cone and room for the tanker hose, while a bagged store needs a sealed floor and a roof.
• Unloading access: a turning circle a loaded tanker can use, and a route that does not cross the production yard.