Airborne Emissions from Si/FeSi Production
direct link: https://link.springer.com/article/10.1007/s11837-016-2149-x#Sec10
Unfortunately for everyone who is concerned, this report reveals that the toxic and dangerous emissions from a silicon plant are much, much worse then we have been told to expect. This is no exaggeration; you are strongly encouraged to read this research material yourselves.
Since this report is self-explanatory and technical in nature, I will present my summary findings first, further details and quotations can be found below.
Summary
As explained over 1 year ago on this blog – virtually all smelters are deadly, toxic and produce dangerous gasses, trace elements and emissions, including greenhouse gases, sulfur dioxide, nitrogen oxides, airborne particulate matter also known as dust, polyaromatic hydrocarbons and heavy metals.
It is not just silica dust that causes silicosis and cancer to be concerned about, it is also the emissions that can (and do) escape from silicon plants into the surrounding environment. None are hazardous-free – not a single one.
The efficiency, design, operation, and handling of materials in the smelter operation is crucial for public and worker safety.
Not all plants are operated at 100% efficiency or safe handling, and even if they are, under the most optimistic scenario – they still produce documented emissions into the environment, which are released into the air, soil and water, thereby exposing humans, wildlife and fauna to their lasting and dangerous effects. These emissions include dioxins, heavy metals, gasses, dust (also called particular matter or PM) which are not all trapped at 100% by baggers, filters and scrubbers.
Plants do not always employ best-practices or technology either, due to cost considerations, available technology, operational skills and experience and accidents. Various studies of silicon smelter plants have been conducted by research experts, their findings clearly show that emissions and toxic chemicals, heavy metals and dioxins pose a environmental and human health hazard to workers and the public.
Both Washington and Idaho residents, County and State Officials have NOT been told the truth regarding these facts. You decide why – but what matters is what a silicon smelter plant actually represents to our region. They are dangerous in all forms, and they pose numerous immediate and long term hazards to human and environmental health.
What You Need To Know From The Research Report
Deadly dioxins are produced and then consumed by the high furnace temperatures, but that does not mean that they are always eliminated (chart shows dioxins still in existence with a semi-closed SAF with semi-continuous charging and off-gas temperatures >800°C @ 4%). Dioxins are among the worst known dangerous compounds known to mankind.
In addition, heavy metals are also produced – "Heavy metals enter the production process as trace elements in the raw materials and electrodes and are redistributed to metal, slag, fume and gas." Heavy metals are extremely toxic to human health and wildlife.
"Some of these metals are vaporized, such as Zn, Pb, Cd, Na, Mn and Fe go into the gas phase and may escape as metal vapor. When the off-gas temperature drops, the metal vapors are condensed and therefore often collected with the dust". So now they've just produced toxic dust.
Table VI shows just how much of these are elements are present in the air, metal and microsilica dust (based on 10 kilotons silicon produced yearly):
"Mercury constitutes a special case among the airborne heavy metal emissions as international legislation has long been stringent with respect to this metal. In silicon alloy plants, the particulate control devices (e.g., fabric filter or wet scrubber) capture the particle-bound mercury. The more volatile elemental mercury is emitted to the atmosphere if no further gas treatment is applied. Hg and Cd levels in the off-gas may be reduced by the use of bag filters with an adsorbent injection (such as activated carbon or lignite coke)"
“Emission estimates to air through the filter systems must cover both gaseous and particle-bound heavy metals, but a major challenge for the estimation is the low concentrations of these elements in the material flows. Mercury typically has detection limits (DL) given in units of parts per billion (ppb) whereas the other heavy metals have DL of the order of magnitude of parts per million (ppm). Hence, very significant measurement uncertainties are introduced and it is often impossible to “close” the material balance for individual elements. The total uncertainty for elements such as Co, Hg and Mo is often around or above 100%. These uncertainties may be lowered by continuous, on-line measurements after the filter systems, but such measurements are often practically challenging. Additionally, large uncertainties are also related to sampling and representability.”
(This is why the "closed-loop" system they're promising is actually meaningless. First off, it's not entirely a closed loop by design. There are large uncertainties introduced and individual elements cannot always be captured. The emissions "estimates" they are providing are simply that - guesswork and empty promises. Give it 10 years and check the public health statistics - then we'll really "know" after a number of us are sick and dead).
Particulate emissions (PM) also pose a particular problem, relying upon filters, scrubbers and baggers to remove these particles (which also include what we call “dust”).
"Airborne PM is an important constituent in the diffuse emissions escaping the plants and may not only affect the air quality inside the plant but also in the local, urban communities as well as the environment at large. The PM may be harmful if inhaled and exposure to high levels of particles has been linked to cancer, pneumonia, chronic obstructive pulmonary disease (COPD) and other respiratory and cardiovascular syndromes."
"Almost all processes involved in silicon alloy production produces PM in some form. In this article, the terms particulate matter and dust are used as synonyms and primarily used for solid particles. The term aerosol includes both liquid and solid particles and the term fume relates to thermally generated aerosols. Table VII provides an overview of the PM sources and a rough estimate of their relative importance to indoor air PM concentrations and to PM emissions from the plant."
"A typical metal yield of between 80% and 90% means that up to 10–20% of incoming Si-units in the furnace escape as fumed silica. Modern ventilation and filter systems have enabled efficient collection of this type of dust and it even constitutes a profitable by-product (microsilica). A typical Norwegian PM emission limit is approximately 30 mg/Nm3."
"The dust from the handling and transport of solid materials, such as the product and the raw materials, is fundamentally different from the dust generated by the active oxidation. It is typically coarser, and the physical and chemical properties depend on the material from which it was generated. Raw material handling and transport can, for example, produce airborne crystalline alpha-quartz which is a health hazard in its own right. No literature on the generation, collection and reduction of the mechanically generated PM in high-Si alloy smelters has been found."
Read the report for full descriptions and better images.
We are not alone with out concerns - virtually everywhere one of these plants are built, there are health hazards and complaints. Iceland for example, has a large silicon plant and a group of disgusted residents have reached out to the world community for help (legal action notice).
Read their story (blog link). Get your facts. They've been fighting this for YEARS.
What they propose for Pend Oreille and Bonner County MUST BE STOPPED. NOW - AT ANY COST.
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