Despite the abundance of raw materials for the production of sodium silicate in Nigeria, research shows that the cost of it from silicate sand is high. However, the Raw Materials Research and Development Council (RMRDC), is partnering stakeholders to convert rice husks to serve as raw materials for sodium silicate production to help save the country N20 billion yearly. BINTA SHAMA reports.
The global industrial production processes are gradually being tailored towards more sustainable use of raw materials with inherent capacity and capability to promote environment sustainability. This is necessitated by increasing environment degradation occasioned by use of raw materials with high tendency for pollution through high energy requirement and emission of obnoxious gases such as carbon dioxide emission, etc, leading to degradation of the environment.
Sodium silicate is normally produced from melting quartz sand with sodium carbonate. The method of commercial sodium silicate production uses calcination of sodium silicate carbonate (Na2CO3) and quartz (SiO2) at 1400 to 1500°C and produces CO2. This method is costly. It also consumes high energy apart from leading to CO2 emission into the environment. As a result, efforts are being geared towards a more sustainable method of production through the utilization agricultural wastes, most especially, rice husks ash (RHA). RHA contain silica in the amorphous form and it is now considered as a renewable raw material for production of silica, silicon carbide and silicon nitride.
Sodium silicate (also called water-glass) is a clear liquid, semi-solid or solid viscous substance with sticky nature. It has a range of chemical formula varying in sodium oxide (Na2O) and silicon dioxide or silica (SiO2) contents or ratios. At present, there are forty (40) varieties of commercial sodium silicate, each with a specific use. Sodium silicates are produced in the form of a variety of compounds ranging from Na2O.4SiO2 to 2Na2O.SiO2 by properly proportioning the reactants. Sodium silicates varying in ratio from Na2O.1.6SiO2 to Na2O.4SiO2 are known as colloidal silicates. They are sold as 20% to 50% aqueous solutions called water glass.
Huge demand for sodium silicate
Sodium silicate has huge demand in Nigeria. Recent annual demand is in excess of 20,000 M Ton per annum. The product has wide applications in various industries for production of silica gel, detergent, packaging industries, cement of glass, pottery and stone ware, fire proof paper, absorbents, abrasive particles, refractory, binder for inorganic paint, preserving eggs and many other applications. The use of 45% sodium silicate as binding material improves the compressive strength of concrete. At present most of the industries in Nigeria import sodium silicate from India, China and Egypt. The top categories of sodium silicate lump imports in Nigeria are sodium silicate HSN 28391900 and HSN Code 2839190000 which includes silicate of sodium, commercial silicates but excluding metasilicates.
According to FAOSTAT, 2018, the worldwide rice and paddy production was over 952 million tons in 2016. The rice husk which is the outer cover of the rice accounts for 20% of the paddy produced. About 190 million tons of rice husk was produced in 2016 alone. Research and Development has indicated that the rice husk has various applications in industries. It is used as an industrial fuel for processing paddy and generation of process steam in power plants. It is also used as a fertilizer and substrate or pet food fibre and as raw material for brick production. RHA is also used as an ingredient for the preparation of activated carbon or substrate for silica and silicon compound production. .
The expanding industrial use of sodium silicate has led to increase in its demand and global production. In 2021, the market volume of sodium silicate worldwide amounted to 26.65 million metric tons. It is forecast that the market volume will grow to around 33.09 million metric tons worldwide in the year 2029. The global sodium silicate market size was valued at USD 6.25 billion in 2021. The market is projected to grow from USD 6.40 billion in 2022 to USD 8.19 billion by 2029, exhibiting a CAGR of 3.6% during the forecast period. The market expansion can be attributed to increasing demand for detergents worldwide, and the growing use of sodium silicate in various applications, such as in water treatment, toothpaste, ceramics production and in synthesis of silica gel, automotive sector, pulp & paper industry and in the construction industry.
Regionally, the global sodium silicate market is segmented into five major regions including North America, Europe, Asia Pacific, Latin America, Middle East and Africa. The global sodium silicate market in North America region is estimated to grow at a CAGR of ~5% over the forecast period due to significant increase in the number of detergent manufacturers and increase in pulp and paper production. Additionally, the expanding number of activities in the region that use sodium silicate, such as tube winding, water treatment, construction, and others, and increasing disposable income per capita throughout the region are anticipated to accelerate market growth. Although, the global sodium silicate market is segmented on the basis of application, into adhesives, detergents, paints, catalysts, refractories, tube winding, and others, out of these, the detergents segment is estimated to hold the largest market share over the forecast period owing to amazing properties of sodium silicate, such as emulsification, wetting, and deflocculating, and rising cleaning expenditure per capita among the global population. According to UNICEF, the average cleaning expenditure per capita was USD 24 in 2020 and it is estimated to increase more in the projection period. As detergent is used widely as a basic cleaning ingredient, the segment is anticipated to hold the largest market share.
Collaborating with stakeholders
Presently Nigeria expends over 20 billion naira on importation of sodium silicate and silica gel annually for the production of detergents, rubber, food and beverage, paper and pulp, paints and coatings, plastics and inks. This is despite the fact that the raw material for the production of sodium silicate is abundant in Nigeria, either from the mineral (Silica sand) or agro-resource (Rice husk). Studies have indicated that the cost of sodium silicate production from silica sand in Nigeria is high and out of reach of many micro, small and medium scale industrialists in Nigeria. In recognition of this, the Council, in collaboration with stakeholders is converting rice husk to serve as raw material for sodium silicate production. According to US Department of Agriculture, Nigeria’s rice production, will not reach five million tonnes in 2022, slightly above the previous year. The US data show a significant increase in production between 2015 and 2017, which then slowed before another jump in 2020 when production reached a high point of 5.04 million tonnes. The area under rice cultivation has also expanded. According to United Nations Food and Agriculture Organization (FAO) the land area under cultivation grew from about 3.1 million hectares in 2015 to 5.9 million hectares in 2018, and then dropped to 5.3 million hectares in 2020. The increment is propelled by the government’s provision of improved seedlings and fertiliser to smallholder farmers and investment in irrigation schemes. In 2014, a scheme to help farmers hire machinery was introduced to improve mechanisation, and in some states, regional governments have granted land concessions as an incentive to large scale commercial farmers. In November 2015, the Central Bank of Nigeria also launched a programme, under which farmers receive loans at favourable rates for rice production.
The annual production of 5.04 million tons of rice in Nigeria will lead to generation of about 1.2 million tons of rice husk and 200,000 tons of rice husk Ash every year. Presently in Nigeria, rice husk is used for cattle feeding, partition board manufacturing and rice husk ash is used in land filling. Rice husk has very low food value and being a fibrous material, it can prove to be fatal for the cattle feeding. Use of rice husk ash or rice husk in land filling is also an environmentally hazardous way of disposing the waste. Despite having so many well established uses, little portion of rice husk produced locally is utilized in any meaningful way while the remaining part is destroyed by burning or allowed to decay in public places in the open air leading to environmental pollution. The reasons for this include lack awareness of its potential, insufficient information about its industrial applications, socio-economic problems, and inadequate processing technology.
The Council has developed and fabricated a liquid sodium silicate pilot plant with a capacity of 500 L/hr using the latest technology so that high-grade sodium silicate could be produced that can be highly competitive in both domestic and export markets. The Pilot Plant is being installed at the RMRDC Technology and Innovation Complex. The most common technology for sodium silicate production is the furnace process. The process consumes high amount of energy and uses virgin resources such as silica sand.