NFU Mutual Smallholding Insurance

Author Topic: Homemade briquettes from recycled materials  (Read 468 times)

Sra

  • Joined Jun 2016
Homemade briquettes from recycled materials
« on: September 27, 2018, 09:52:14 pm »
In my real world job I’m a DT teacher and currently have an A Level pupil who is designing a device for manufacturing briquettes from recycled paper, card, or sawdust. There are several simple hand presses on the market for £20 (slow and only good for low volume) and a fair few homemade scrap heap challenge versions on Utube for larger production runs but not really much commercially available at this scale. His theory being brown card, saw dust and since the advent of GDPR shredded paper are easily available for free and could provide a sustainable source of fuel for a multi fuel stove

His aim is to make a machine capable of making 100-200 blocks an hour that is economically viable to purchase.

The first stage of a DT project is research so I thought I would share some of what we have found out in case it is of interest to anyone - feel free to post any insights you think he might find useful - I will post his design as it progresses from drawings to final testing.

I will add to this post some of the findings to date.
Voss Electric Fence

Sra

  • Joined Jun 2016
Re: Homemade briquettes from recycled materials
« Reply #1 on: September 27, 2018, 10:05:06 pm »
Test 1 - you can buy commercially made briquettes made out of compressed sawdust/ shavings. Can this be done on a smaller scale with easily available components? Eg 30t hydraulic press and some 75mm steel tube with a 1.5mm wall.

Answer - seems not. Tried shavings, sawdust and wood flour. Pressure is enough to create a solid block and even to cause the tube to bulge but the resulting pellet just crumbles when touched.

Test 2 - will soaking in water improve the bonding of the material.

Answer - yes but only temporarily, once dry it still crumbles

Unsurprisingly you get a better result with finer material

Internet research shows much higher pressure is required which effectively liquifys the lignin in the wood to bond it together. Might not be correct but we have ruled out wood only as an approach

doganjo

  • Joined Aug 2012
  • Clackmannanshire
  • Qui? Moi?
    • ABERDON GUNDOGS for work and show
    • Facebook
Re: Homemade briquettes from recycled materials
« Reply #2 on: September 27, 2018, 10:15:53 pm »
I have one of the hand type units, which I have used to make briquettes for my wood burning stove.  I use a mixture of torn up documents and newspaper, and it is very successful - if I have the time and space to make them and lay them out to dry. 

These briquettes don't fall apart.  My motivation is recycling my own excess paper, but I doubt I would buy these in any quantity, even if it was recycling other people's documents.  Perhaps becasue it is easy to buy or obtain wood.

HTH
Always have been, always will be, a WYSIWYG - black is black, white is white - no grey in my life! But I'm mellowing in my old age

Sra

  • Joined Jun 2016
Re: Homemade briquettes from recycled materials
« Reply #3 on: September 27, 2018, 10:21:11 pm »
Test 3 - how effective/efficiencent are the £20 hand presses for making paper/card briquettes?

Answer - Not great. At best you can do 10 blocks an hour, it is a very messy process, the compression is poor and the end product is still very wet as there are not enough routes out for the water.

The one we have bought is already showing wear and has distorted due to the force of pressing it down hard. A quick evaluation shows spot welded joints which water gets between - won’t last long once it starts to rust.

Test 4 - do the blocks hold together and what materials are best

Answer - yes with a big BUT. Our first test of 1/3 each sawdust, card, and paper failed despite soaking for 24 hrs and blitzing with a concrete blender on a power drill. Soaked for a week as recommended on some web sites did work - appears patience and planning are required for anything other than shredded paper.

It did prove adding paper and card can bond some sawdust into a usable block

Sra

  • Joined Jun 2016
Re: Homemade briquettes from recycled materials
« Reply #4 on: September 27, 2018, 10:42:35 pm »
Test 5 - Does adding a hole in the middle of the block (done by adding a length of 20mm plastic tube halfway through packing and pushing it out of the finished block) really improve drying times?

Answer - Resounding Yes

Having force dried the first test blocks in a kiln at 80 degrees for 48 hrs the blocks were equally hard and dry to touch. Cut in half with a bandsaw and tested with a digital moisture meter the block with a hole was showing a maximum of 10% anywhere on the block (good for seasoned wood). The solid block was 10% externally but 60% in the middle.

Conclusion - The hole is worth it in terms of drying how it affects burn times on equally dry blocks is a later experiment.

Sra

  • Joined Jun 2016
Re: Homemade briquettes from recycled materials
« Reply #5 on: September 27, 2018, 10:51:18 pm »
Currently we are drying batches of different mixes of paper card and wood to find which is the best in terms of burning. Obviously burn time, heat, and total energy are all factors.

Test 6 will see him in the chemistry lab analysing samples for energy content

Test 7 will be a more subjective test in a stove looking at burn time and heat output (using a laser heat gun)

Test 8 will look at how the hole in the middle affects burning

Given the amount of blocks we are drying it will be a few weeks until I can post the results of these....

Please add any advice or experiences - it will all get passed on to the lad and is extra research he can add to his portfolio   :D

 

Gripple fencing materials

Started by tobytoby

Replies: 4
Views: 1850
Last post January 06, 2012, 11:39:29 am
by cooper956
Homemade Incubator

Started by The Relic

Replies: 6
Views: 3305
Last post April 07, 2009, 01:41:24 am
by rustyme

Forum sponsors

FibreHut Energy Helpline Thomson & Morgan Time for Paws Scottish Smallholder & Grower Festival Little Peckers

© The Accidental Smallholder Ltd 2003-2019. All rights reserved.

Design by Furness Internet

Site developed by Champion IS