Design of Belt ConveyorsStep #1 Belt Size and Speed2012 Dr. B. C. PaulNote Material in these slides include screen shots from the program Belt Analyst by Overland Conveyors. Credit for program and interfaces are given to Overland Conveyors. Procedures taught and many tables used were developed by the Conveyor Equipment Manufactures Association. The author also referenced previous notes developed by the author.

General Design of Belt ConveyorsCEMA has developed a series of tables and equation checks.Conveyors are designed by identifying the taskGuessing by experience or tables what types of parameters or equipment to useThen checking those designs against the design criteria and making changes as needed.

Belt AnalystBelt Analyst is one program available to perform this taskAs you input parameters, Belt Analyst will try to automatically select appropriate equipment or other needed valuesYou have some over-ride opportunitiesIn the end Belt Analyst will help you examine the performance of the belt and provide hints as to when you may want to alter a design.

Starting InformationWe assume you know how much material you would like to moveWe assume you know what your material isWe assume you know the route over which you would like to move the material

A Case StudyI am going to select a mainline belt for a coal mine with rolls in the floor.Im going to move 4 million tons of ROM coal each yearIll move that in 250 days per year with an assumed 14 hours per day of actual run timeThat makes about 1150 tons per hour

Start Belt Analyst

Belt Analyst Fires UpNote that design steps areDesignated by icons down theLeft side.

Input My Project DescriptionPeculiarity If I want to name myFile I have to do a File / Save As

I cannot directly input the filename.

Select My UnitsClick on Units to Drop down a menu

I will want to do English units. (BeltAnalyst often attempts to default toMetric)

Im Going to Start Entering My TonnageI need to get a handle on myTemperature, belt speed, andBelt width

TemperatureIts pretty constant in an underground coal mineAbout 69 FIf I were doing a decline belt with winter air sweeping in this would be a very different story

Rule of Thumb for Initial Belt SizeFor a Belt Width the Minimum for a chunky material is 5 times size of largest chunksIf we figure largest typical chunks are 7 inchesSuggests about 35 inch conveyor

CEMA Table Suggests About 600 Feet Per Minute600 fpm maximum

From the Width Drop-Down Select a Standard Size

Complete My Input and Pick My Design StandardI want to use the latest CEMAStandard the 2005 CEMA 6th

Click on CEMA 5 to trigger aDrop-down.

Time OutWhat is this CEMA 5, CEMA 6, and DIN business?CEMA standards have a rating system for how heavy duty different parts areYour picking how your parts listing will be rated (example a CEMA C6 idler C means its medium duty unlike A and B light duty, and 6 means its six inches in diameter)

The Friction IssuePulling things along on a belt creates a lot of frictionYou have idlers rollingYou have material rubbing up and down against itself as the belt sags between idlersYou have the belt flattening and squishing on the idlersYou have rubbing from everything that touches the conveyor

Friction IssuesThe more friction you have the harder the motor must pull to move the conveyorIt impacts your motor sizingThe more you pull the stronger the belt has to be to not breakThis impacts your belt choiceThe more you pull the bigger a deal slipping on drive pullies is

Standards and FrictionFriction is usually estimated from empirical laws and past observationDifferent standards have broken this estimation down differentlyCEMA is usually the most careful to break things down with precision (DIN methods may simply ask you to pick a friction factor from a single table)

Next Im Going for My Idler Troughing AngleI will select this by clicking on theIdler troughing symbol at the side ofThe screen.

A Comment on Data Entry Order in Belt AnalystSome of our software (such as FPC) strongly suggest you go through panels in the order the tabs are placedThis is less true of Belt Analyst which recalculates and re-estimates each time you add new informationIn my case I want to get a belt size and speed right for production before anything else

I Did Select CEMA 6 at the TopBut the program selects values shown in blue unlessYou over-ride with other information.

35 - 3 roller idlers are standard for coal so Im Ok

Next I Will Set My Material (ROM Coal)

From the Drop-Down I Select ROM Bituminous Coal

Im Going to Over-Ride a DefaultI said my maximum lump size was7 inches.

Ill type it in and hit return

At This Point I Note A ProblemBelt Analyst Used RedMessages to warn idiots thatTheir design if failing.

In my case putting 1150Tons per hour of coal onA 36 inch belt going 591 fpmIs causing my belt to loadTo 122% of capacity(80-85% is usual designTarget). Unless I want to doSome serious belt shovelingI had better rethink.

The Belt Capacity IssueIdler AngleBelt SizeSurcharge AngleSeveral parameters determine theMaximum possible cross-sectional areaYou can put on the conveyor

(Note Surcharge Angle is less than theAngle of repose because remember thisMaterial is actively bouncing along on aBelt ride)

If the load is all the way up to the edgeOf the belt and stacked to maximumSurcharge we would call the belt 100%Full.

So Why Do We Want to Keep the Belt Fill Down?Obviously if the materials is stackedHigher than it will stand it will spill

Material on a conveyor is not all fineLittle particles what happens if a Big chuck slides down to the edge?

If there is no extra catch room ofUnloaded belt it will go over the edgeAnd mining interns and other workersWill end up shoveling the belt line.

Choose My SolutionI can get 87% load with a 42 inch belt at 600 fpm or 79% load with 48 inches at 500 fpm - Im going to go for some expansion room

One More Check for Material SpillGo to the material tabThe concern is edge distance

What Happens if a Maximum Size Lump Falls to the Edge?Could it get brushed off andBecome a spill?

For Bituminous 5.9 inches is thetypical top size for ROM IInput 7. If I am really believingThis is true I may need toSpeed-up or increase the size ofMy belt.

Now You Dont Want to Be Left Out.Conveyor Assignment #1 Plan a section belt from a Room and Pillar Super-Section at about 800 tons per hourAssume regular ROM Bituminous Coal with 5.9 inch lump sizeUse Belt Analyst to get a well sized belt with a reasonable speed to handle the materialSubmit your Belt Analyst File and an answer sheet giving the belt size and speed you selectedExplain why you believe this size and speed is suitable