Block Making Machine in Sudan: Water Sets the Output Ceiling

A block making machine in Sudan is limited by water and curing, not by the press. Hydraulics reach 31.5 MPa and the table vibrates 3,800 to 4,500 rpm, yet none of that matters if the green block dries in the first hours after it leaves the mould. In dry desert air a block can lose its surface water before the yard crew has stacked the pallet, and strength lost that day does not come back at 28 days. So the real ceiling on output is the water you can deliver per shift, the cover you can hold over the yard for 7 days, the dust control that keeps motors alive, and the generator that carries the line. This article works through that arithmetic.

1. Water and curing set the output ceiling, not the press

A press repeats the same stroke all day; curing is what turns that stroke into a block a buyer will accept. Semi-dry concrete leaves the mould with almost no free water, so the first 24 hours decide the surface. Where afternoon air passes 40 degrees Celsius and humidity falls under 20 percent, an uncovered block loses moisture fast, the cement at the face stops hydrating, and the skin powders under a fingernail. That dusting is not cosmetic: the block keeps its core strength and still fails on abrasion at the face. Our rule on dry yards: hold the product damp through the first 7 days of a 28 day cure, keep the stack under film or misting lines, and cast green blocks early and late in the day rather than at noon.

2. Sizing the reservoir from the shift target

Take a QST1200 producing up to 120,960 standard bricks in an 8 hour shift. A dry mix carrying about 6 percent water by mass, with the water to cement ratio held between 0.42 and 0.50, puts roughly 0.15 to 0.20 kg of mixing water into one 240 × 115 × 53 mm standard brick. Across the shift that is about 18 to 24 t of mixing water, which is 18 to 24 cubic metres, or 2.5 to 3 t an hour. A twin shaft mixer in the QS-1200 range delivers 25 to 75 cubic metres an hour, so the mixer is never your limit. The tank is.

Curing water is different: it is lost to air, not absorbed. Misting a covered stack takes about 2 to 3 litres per square metre per day, while an open water surface in dry air can give up 6 to 10 mm of depth a day to evaporation. A covered 40 to 60 cubic metre tank carries one shift of mixing plus a day of misting. Cover the tank: an open reservoir loses volume to evaporation and collects grit that clogs nozzles.

3. Dust is a wear item: mixer, vibration motors, pallets

Dust attacks a block plant in three places. The mixer throws a cloud at every batch, and that cloud settles on motor windings and on the cooling fins of the vibration motors. A finned motor running 3,800 to 4,500 rpm under 150 kN of exciter load will overheat long before the bearing fails. Fit extraction at the mixer mouth, blow the fins with dry air weekly, and check terminal box seals at every service. The second target is the hydraulic system, where fine grit passing a tired breather becomes a lapping paste inside the pump.

The third and most expensive item is the pallet. Our standard pallet for this class of machine is 1,350 × 880 × 25 mm, and abrasive sand works on both the deck and the edge rails. Measure the deck at four corners weekly, not by guesswork: when thickness drops from 25 mm toward 20 mm, or the pallet rocks on a flat plate, retire it. A pallet out of flat by a millimetre shows up as height variation on every block, and the mould takes the blame.

4. Weak grid: 37.4 kW or 88.4 kW decides the generator

The QT5-15 is the smaller route: total power 37.4 kW, forming pressure 25 MPa, exciter force 58 kN, cycle 15 to 20 seconds and a host weight of 6,900 kg. A complete line around it commonly installs 60 to 90 kW. The QS1500 sits in another class: total power 88.4 kW, 31.5 MPa, a 720 mm main cylinder bore, a 20 to 25 second cycle and about 39 t of machine weight. On a site that must run on diesel, that gap is not a detail. Starting current sizes a generator, not running load, and the largest motor on the line decides the set.

Our rule: the set must exceed the total installed draw of the line and carry the starting current of the biggest motor, several times its running current on a direct online start. A 37.4 kW machine line can be carried by a much smaller set, and diesel burn follows the load at roughly 0.2 to 0.25 litres per kWh, so the fuel bill scales with the choice. Where the set stands in blowing sand, add a cyclonic pre-cleaner. Send us the voltage, phase and frequency your electrician measures at the panel; we build the control panel around that answer, not an assumption.

5. Container math and yard prep before the machine ships

A machine 11,500 mm long with a 2,800 mm frame height does not travel assembled. A 40 foot high cube offers roughly 12,032 × 2,352 × 2,698 mm of internal space and a standard 40 foot box is only 2,393 mm high, so the main frame, hopper, conveyors, pallet feeder and stacker ship as crated sections. Site assembly and commissioning normally take 7 to 15 days. Book the crane for arrival day, and check the turning radius from gate to foundation pad with your largest trailer.

Prepare the water and curing side of the yard before any steel arrives. Lay the reservoir and the misting line first, pour the curing slab where the green blocks will stand for 7 days, and cover the aggregate bay so the sand does not arrive hot and dusty. Buyers in Khartoum and Omdurman normally find aggregate close by; what is scarce is shade and water. Let the machine schedule follow the yard, not the reverse: a plant that starts moulding before the reservoir is filled produces blocks nobody should sell.

6. What we confirm before quoting a block machine

We do not send a configuration until the answers come back in writing, because the same machine is built differently once the power, the water and the yard are known. The list below is the one we use for every dry climate project.

• Power on site: load in kW, phase and frequency, measured at the panel by your electrician, and whether the plant runs on the grid, a generator or both.
• Output target and block sizes: 390 × 190 × 190 mm hollow, 400 × 200 × 200 mm or a 240 × 115 × 53 mm standard brick, plus the strength class the buyer tests.
• Water: the source, the hours it is available, and the reservoir volume you can build, because that figure sets the shift target more often than the press does.
• Dust and heat: whether the yard shades the aggregate, how often the crew cleans cooling fins, and the cover over the curing stack.
• Yard and unloading: pad layout, curing slab area, crane or forklift capacity at the port and plant, and the tightest gate on the route.