Sand Sorter Update April 2011

Sand Sorter Update April 2011

Comments or questions:Post to BSF-Production Group: [email protected]

Or contact: Derek Baker ([email protected]) or Olivier Mills ([email protected])

For previous updates go to: Biosand Filter Production Group http://groups.google.com/group/bsf-production?hl=en

Sand Sorter Update –April 2011 www.cawst.org 1

mailto:[email protected]



http://groups.google.com/group/bsf-production?hl=en

Sand Sorter Update –April 2011 www.cawst.org

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Outline: Purpose and Objectives

How the process works

Design of Sand Sorter – History & Progress Ron Ryde’s ‘Original’

‘Alpha’ - 2nd design

‘Beta’ – 3rd design

The ‘Zambia’ Sand Sorter

The ‘India’ Sand Sorter

What we learned in Zambia & IndiaPositives

Problems

Solutions

Next Steps and Future Plans

Purpose and ObjectivesPurpose of the Sand Sorter: To support the growth of biosand filter (bsf) production in the world; a machine is needed that can prepare the filtration sand and achieve higher quality and greater quantities than manual sieving and hand washing.

Objectives:• A ‘fit-for-purpose’ machine design to prepare sand & gravel that meet the

specifications for biosand filters.

• Capable of being fabricated, operated and repaired in developing countries.

• Open-content; free dissemination and cooperative improvements shared among bsf producers.


How the process works

• Sand and gravel, saturated in water, is passed over 3 vibrating screens to sort and wash the sand into the specific sizes required for the biosand filters.

• Changing the selection of the 3 screens provides the sizes needed for the filtration sand, separating layer and underdrain layer.

• Water is used in the process to wash the very fine material off the sand and gravel. In this way the sand sorter both sieves and washes the sand & gravel in one operation.


Ron Ryde’s ‘Original’

First design; Designed and manufactured by Ron Ryde in N. America and transported via suitcase into Haiti and Zambia.

Ron Ryde’s original design provided the basis and the stimulus for a design that could be built in-country…a task that CAWST undertook in 2009.


Design of Sand Sorter - History

Ron Ryde’s Original Design

Operating in Haiti…

and in Zambia


Objectives for ‘Alpha’ - 2nd design; 1. Develop a prototype Sand Sorter

that is sufficiently flexible to modify the important parameters to further progress the design.

2. Fabricate a transportable model that can be used and demonstrated in various locations (in Canada).

3. Generate drawings for fabrication.

4. Conduct trial testing to determine quality of products, throughput capability, and ease of use and maintenance.



Objectives for ‘Beta’ – 3rd design; 1. Design an affordable, effective and

workable Sand Sorter that can be fabricated in the developing country where it will be used.

2. Develop the drawings, photos and instructions for fabrication for the local skills and materials that can be located in developing countries.

3. Produce a prototype that can be trial tested for quality of products, throughput capability, and ease of use and maintenance.



Changes include:

• Revised design for available steel sizes

• More weight (of steel) meant frame needed reinforcement

• 1725 rpm motor was not available; needed different pulley sizes to reduce down to 915 rpm


Kirk Schauer, Director, Seeds of Hope International Partnerships

The ‘Zambia’ Sand SorterOctober 2010

The first sand sorter of this design fabricated ‘in-country’

The ‘India’ Sand SorterMarch 2011

- The biosand filtration sand will be prepared in Ranchi, Jharkhand and trucked to other biosand filter projects such as Kolkata, West Bengal.

- All the components could be found in NE India, however the larger the city the easier it was to find the correct steel dimensions and mechanical components


Dhayang Norbu, Manager Biosand Filter Program Lalita, Coordinator

Community Health Promotion

The ‘India’ Sand SorterMarch 2011

Full operation requires additional equipment: - Stationary feed

hopper - Stationary discharge

chute- Platform for

operator Space was allowed for two more ‘in-line’ sand sorter machines


What we learned in Zambia & India• The sand sorter can be successfully built ‘in-country‘ • Cost is roughly $US 2000; about $1200 for machine plus $U800

for the stationary feed hopper & discharge chute and platforms • Equipment and tools needed:

– Arc welder, drill press, metal chop saw, hand drill, hand grinder, vise, clamps, right angle square, wrenches, steel punch, caliper, hammer

• Sourcing of most components was possible in Zambia; all components could be sourced in India.

• Obtaining steel of the correct dimension, especially flat bar & angle iron, is important since the design is based on these sizes.

• The frame needs to be well braced and the base of the frame needs to be cast in concrete.


• A water recycle system using multiple settling tanks, with a submersible pump in the last tank, allows the wash water to be reused continually

• The undersize material is most easily handled by allowing it to drop down onto the floor below rather than a discharge chute

• A sloped floor below the sand sorter and running to the first water recycle tank makes it easier for the larger particles (of the ‘undersize’ material) to be removed from the water.

• The hook edge on the screens can be made using galvanized sheet metal or by sandwiching the screen between flat bars.

• The water spray system is not really needed and removing it provides much better access to the top screen. Hand-held hoses are preferred by the operators.


What we learned in Zambia & India


Positives:1. The vibration motion was very effective and consistent – the

eccentric orbital motion never dampens.2. The screens could be changed easily and quickly for cleaning

(hook edge screens, tension rail and wedge system)3. Sand sieve analysis showed that filtration sand could be

produced within the specifications recommended by CAWST4. Production capacity was good. Quote from Kirk at SHIP:

“Although I still don't know the upper limit because of one thing or another …with a smaller crew we are still able to see the production numbers grow a lot…”



Problems:1. The flange bearings were difficult to align correctly; the

two eccentric sleeves must be in line with one another to get the correct motion.

2. The flange bearings moved along the shaft during the initial days of operation in Zambia and had to be tightened 3 different times.

3. After about one week of operation the 0.6 mm galvanized sheet metal used for the discharge chutes failed along the hook edge where they are fastened to the vibrating frame. It was determined that the durability and longevity of this sheet metal is not adequate.



Solutions:1. For the sand sorter fabricated in India (March 2011) the

flange bearings were aligned correctly and kept from moving by inserting a ‘set screw’ in the two eccentric sleeves to fasten them to the shaft.

2. The design of the discharge chutes was changed to 1.5 mm sheet metal welded to the vibrating screen housing and reinforced with angle iron. This material is now also used for the feed tray.



Eccentric flange bearings

A set screw was placed in the India ‘Reiss Ryde’ Sand Sorter to prevent the bearings from moving out of place


Discharge chutes were welded onto the vibrating frame and reinforced with angle iron

Zambia India

Sieve ScreensThe 3 screens and ‘catch pan’ are held in place with ‘tension rails’ designed to make it easy to remove and reinstall the screens.

Screens are tensioned with wedges to transfer the vibration energy and to reduce screen wear.


Hook edge on screen

Base of the frame should be cast in concrete.


A sloped floor leading to water recycle


Stationary feed hopper

Stationary discharge chute


Product bag

Submersible pump

Water recycle

Next Steps & Future Plans

1. Revise drawings for design changes from Africa and India experiences.

2. Release: CAWST Sand Sorter Version 1.0

3. Generate instructions for fabrication including:• Steel order, cut list, materials legend and details of mechanical

components for in-country fabrication

• AutoCAD drawings, photos and notes for fabricator

4. Survey operators for learnings on Sand Sorter

5. Develop lessons-learned and best practices for bsf implementers using sand sorter machines


Sand Sorter Update April 2011

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